Add support for "rgba" to Phaser.Stage.backgroundColor

 - backgroundColor now uses valueToColor which supports hex strings, web/rgba strings, and hex numbers.
 - valueToColor normalizes across hexToColor/webToColor/getRGB; see comments
 - hexToColor now documents the prefix being optional and allows the `0x` prefix.
 - webToColor now exctracts an alpha channel if present - as a slight misfeature it will also accept `rgb(..,a)`.
Fixed return value of Polygon.contains

Polygon.contains was toggling the return value on each valid hit.
Minor documentation cleanup
Updated Color.webToColor to accept [more] spaces

 - webToColor now accepts arbitrary spaces, which are allowed per CSS rules (percents still not supported)
Merge pull request #1265 from Singularetantum/dev

Fixed return value of Polygon.contains
Merge pull request #1264 from pnstickne/wip-1234

Add support for "rgba" to Phaser.Stage.backgroundColor
Merge pull request #1261 from spayton/dev

Texture width is recalculated larger on subsequent call to updateText() ...
Fix for Key.enabled issue #1190

- Added `enabled` getter; this resets the key (soft) and then disables they key
- Added `_enabled` property and updated internal usage
- Updated document for `reset`.
Comment fix

- Added `@private`
Merge pull request #1271 from pnstickne/wip-1190

Fix for Key.enabled issue #1190
Polygon.contains was toggling the return value on each valid hit (thanks @Singularetantum #1265 #1266)
Text.updateText was incorrectly increasing the size of the texture each time it was called (thanks @spayton #1261)
Phaser.Polygon has been refactored to address some Pixi v2 migration issues (thanks @pnstickne for the original implementation #1267)

Polygon.area is now only calculated when the Polygon points list is modified, rather than on every call.

Phaser.Polygon can now accept the points list in a variety of formats: Arrays of Points, numbers, objects with public x/y properties or any combination of, or as a parameter list (thanks @pnstickne for the original implementation #1267)

Polygon.contains now correctly calculates the result  (thanks @pnstickne @BurnedToast #1267)
Small refactor to pass jshint.
Update phaser.d.ts
Merge pull request #1276 from clark-stevenson/patch-5

Update phaser.d.ts