* 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.

* First fix for opening clusters, added unit tests

* Added opening of child cluster to parent cluster

* Added more tests for multi-level clusters

* Commenting fixes

* Added unit tests for option allowSingleNodeCluster, fixes due to that

* Added test for allowSingleNodeCluster with nested clusters

* Fixes due to linting

* Removed TODO from code

* 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