* The next fix on Travis unit test failure

This is the next escalation on the war against the Travis unit tests failing (which came into being by yours truly).
By accident, I could recreate the unit test failure on my development machine. This led to a more directed effort to
squash the bug.

The insight here is that test `(window === undefined)` fails, but `(typeof window === 'undefined`)` succeeds. This undoubtedly has to do with the special status `window` has as a global object.

Changes:

- Added check on presence of `window` in `Canvas._requestNextFrame()`, fixed local source errors.
- Added catch clause in `CanvasRendered._determinePixelRatio()`
- small fix: raised timeout for the network `worldCup2014` unit test

* Preliminary refactoring in utils.js

* Added unit tests for extend routines, commenting and small fixes

* More unit tests for extend routines

* - Completed unit tests for extend routines in
- Small fixes and cleanup in `util.js`
- Removed `util.protoExtend()`, not used anywhere

* Added unit tests for known font options

* Interim save before trying out another proto chain strategy

* Fixed problem in first example #3408

* Removed silly file that shouldn't be there

* Added unit test for multi-fonts

* Comment edits

* Verufy unit tests, small adjustments for groups

* Further work on getting unit tests to work. PARTS NEED TO BE CLEANED UP!

* Further tweaks to get unit tests working

* All unit tests passing

* Fixes due to linting

* Small edits

* Removed prototype handling from font pile

* Fixes during testing examples of #3408

* Added unit test for edge labels, small fixes

* Added unit tests for shorthand string fonts; some tests still failing

* All unit tests pass

* Removed Label.parseOptions()

* Completed shorthand font tests, code cleanup, fixed choosify for edges

* Addressed review comments

* Addressed review comments, cleanup

* Added unit test for Array.prototype mangling - first passing version

* Enhanced unit test for prototype stressing to catch more illegal for-in loops

* Fixed all for-in linting violations

* Corrects usage of @static jsdoc annotation

* Correct unresolvable types

* Correct types in jsdoc and remove extraneous @class & @constructor jsdoc

* Remove incorrect @static jsdoc

* Adds missing jsdoc for param copyFromGlobals

* correct jsdoc in util

* Corrects casing on jsdocs

* Swaps @inheritDoc to @ignore for constructors where constructor args are documented in the class

* Instantiates Errors with `new`

* Addresses improperly defined @callback tags.

* Split callbacks out to separate jsdoc

* Moves constructor jsdocs back to constructor and drop @ignore.

* Enables require MethodDefinition for require-jsdoc lint rule and corrects 66% of missing Method Definitions

* Adds jsdoc for all remaining methods and corrects @class/@constructor documentation

* Define values more accurately

* Correct bugs that prevent jsdoc generation

* Removes redundant .eslintrc from graph3d, lints the rest of the code base, and enables valid-jsdoc lint rule

* Corrects lint violations

* Update hierarchy when node level changes

Fix for #3220

On change of data of an existing node, the level is checked for changes.
If changed, for a recalculation of the hierarchical layout.

The fix does not explicitly check for hierarchical layout; this should not be a problem.
The added code can be used to add further node fields which may trigger recalculation of layout.

* Changes due to review

The returned node id's were exactly the wrong way around;
'to' returned the parents, 'from' returned the children.

This fix swaps the tests for determining which to return.

* Protect Network from zero and negative mass values

Fix for #3133

Option-field 'node.mass` must be >= 0.
Checks have been added at the nodes level, for both nodes-global and nodes specific options.
In addition, an internal check has been added for `NodeHandler.defaultOptions`.

The documentation has been adjusted for this change.

* Fix whitespace

* Added param 'direction' to Network.getConnectedNodes()

* Redo commit - Network.js does not need to change

* replacing all ES6 imports with CJS require calls
resolves #2934
used the following regex to apply the changes in lib:
s/import\s+(\w+)\s+from\s+(.*);\s*$/var $1 = require($2).default;/
s/import\s+(\w+)\s+from\s+(.*)\s*$/var $1 = require($2).default;/

* cleaning up inconsistencies

* Refactor propagateFonts(), first working version. Default font  for 'mono' is now 'monospace'

* Tested and cleaned up refactoring changes

* Network: use separate refresh indicator in NodeBase, instead of width parameter

* Added usage of iBaseNode.doRefresh to image shapes.

* Rearranged code in NodeBase.needRefresh()

* Fixes for review

* Removed strange link

* Added 's' in needsRefresh(); typo fix

* Fixes for review, code cleanup

* Modified ratio calc to original working.

* Made code in CircularImage.resize() more sensible.

* Multifont node and edge labels
* adjust documentation
* rework mod-font property inheritance
* Node max/min widths, min heights; Edge max widths
* Accumulate sizes correctly for unconstrained multipoint labels
* handle font.multi when groupOptions.font is not declared
* propagate label fonts on changes, not just creation
* Allow top-level constraint numbers
* accumulate width and empty lines appropriately

- Added interpolation option for interpolation of images, default true.

- Fixed #1528, #1278, avoided ID's being cast to string for methods that return ID's as well as storePositions casting to string.

Node labels don't currently make use of the 'align' property, so this reuses
the existing property.

The label code has a number of alignment options that make sense to edges only,
so the Edge/Node now passes a boolean to the Label ctor to explain which the label
is being rendered for

Will only apply to Network nodes with a shape: 'box' property, as most
other shapes this will not make sense for. This enables the box shape
to be used, for instance, for diagraming CFG data from source code.

Replaced dashes property in options.js with a shapeProperties object containing a borderDashes property.
Replaced dashes property in defaultOptions in NodesHandler.js with shapeProperties object having its borderDashes property set to false.
Created implementations of enableBorderDashes and disableBorderDashes functions in NodeBase.js
Updated CircleImageBase to use enableBorderDashes and disableBorderDashes for enabling/disabling dashed borders.
Added to ShapeBase enableBorderDashes and disableBorderDashes calls to allow all shapes that have borders to have the dashed borders feature.
Updated example demonstrating how to apply the dashed border to a circularImage node
Created example demonstrating how to apply the dashed border to a all shapes that support dashed borders.
Updated documentation explaining the usage of the shapeProperties.

Added the following:
- dashes property to nodes in options.js
- dashes property with value false to defaultOptions in NodesHandler.js
- support for Arrays to selectiveNotDeepExtend function in util.js
- functionality to CircleImageBase.js that allows circularImage nodes to have dashed borders
- example demonstrating how to apply the dashed border to a circularImage node
- documentation explaining the usage of the dashes property on a node

- Added beginnings of unit testing for network.