* Network: Fixes sorting on Layout sorting, refactoring.

Fix for #3403

Chromium has divergent behaviour on sorting of `undefined` values, a check has been added for these.

The fix itself is small, it adds a check on `undefined` in the sorting function(s).

In addition:

- Fixed off-by-one error on tree index
- Refactored away checks on visibility by replacing `_isVisible()` with a Strategy pattern for direction

The latter removes a long-standing eyesore in `LayoutManager`; it's probably also faster.

There is some hope that these fixes will improve the hierarchical layout initialization, which has had
problems for quite a while.

* reformat code block

* Add next attempt to fix Travis unit test bug

* Fix unit test - timeout

* Adjustments for comment reviews

* Moved direction strategies to separate module; added fix for 'window is undefined'

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

* added hexagon shape to the node.

* Updated function for hexagon shape.js

* Modifid the shape login for hexagon

* Remove this.translate from the Shape.js for hexagon

* updated hexagon draw logic

* Fixed code review comments and update the branch

* Updated changes in test.js

* 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

Fix for #3367

Changes:

- Clustered nodes with shared connections are added to the same cluster
- joinCondition value `null` handled as `undefined`
- Fixed bug on adding clusters if joinCondition present and returns true

Unit tests have been added to `Network.test.js` for these changes.

* Added commenting for options, refactored choosify()

* Refactored updateLabelModule()

* added comment at node creation

* Completed fix for #3350

* parseOptions() different handling for bridged/extended; unit tests for reversal of options

* Fixes on linting and unit testing

* Enable unit testing for module Network

Adds mocks for certain components, in order to let module `Network` be run in unit tests.

Changes:

- Create a mock object for `hammer.js` when running browserless. The inspiration is taken from [here](https://github.com/uber/deck.gl/pull/658)
- Create a mock function for `window.requestAnimationFrame()` when running browserless in `network/modules/CanvasRenderer.js`
- Added unit test for `Network` to show that unit testing for it now works
- Fixed naming of container in `test/Graph3d.test.js`

Since `hammer.js` is also used in other modules, this fix is potentially an enabler for full-module unit tests for those as well.

* Cleanup unit test Network

* Fix for unit test

* Added example networks to unit test

* Fix error in loading disassemblerExample

* Network unit test final fixes

* Adjusted comments

* First working version of updating clustered edge

* Added fix for #1315 as well

* Enable unit testing for module Network

Adds mocks for certain components, in order to let module `Network` be run in unit tests.

Changes:

- Create a mock object for `hammer.js` when running browserless. The inspiration is taken from [here](https://github.com/uber/deck.gl/pull/658)
- Create a mock function for `window.requestAnimationFrame()` when running browserless in `network/modules/CanvasRenderer.js`
- Added unit test for `Network` to show that unit testing for it now works
- Fixed naming of container in `test/Graph3d.test.js`

Since `hammer.js` is also used in other modules, this fix is potentially an enabler for full-module unit tests for those as well.

* Cleanup unit test Network

* Added unit test for fix issue #1218

* Adding test for #1315 - Interim save

* Completed unit test and fixes for #1315

* Added fixes for #1291

* Added unit test for #1219

* Added header comment for Clustering.js, small fixes

* Fix for unit test

* Added example networks to unit test

* Fix error in loading disassemblerExample

* Network unit test final fixes

* Fixes for linting

* Fixed essential typo

* Fixed linting error

* Fixed unit test

* Fixed unit test again