API / documentation consistency updates

- The `disabled` property of various input classes has been inverted to `enabled`.
  Direct/internal usage of `disabled` has been transformed to `!enabled`.
- A `disabled` get/set property has been added to wrap `enabled`, and marked as @deprecated
  This ensures current API compatibility.
Updated documentation per current Phaser tag usage
ScaleManager

 - Specific bug fixes (example)
   - Scale modes can now be set independently
   - Switching between fullscreen and normal correctly restores modes
   - Alignment does not incorrectly offset in fullscreen mode
   - Changing scale/alignment promptly refreshes layout
   - `isFullScreen` returns a boolean, as it should
   - Faster parent checks (if required)
   - NO_SCALE should not not scale (vs previous behavior of having no behavior)
   - Correct usage of scaleMode depending on mode

 - Removed / unified code-paths, which helped address several issues
 - fullScreenTarget adjustment/restoration is less brutal
 - Updated documentation
 - pageAlign* works as alignment on the containing element. It should still work were it worked before (so this is not a breaking change) as well as being more universal.
 - Added @protected and @private attributes
   - Some methods were (implicitly) @public even though using them out of context is invalid

 - API Breaking:
   - Renamed some INTERNAL/@private methods
     - Should only affect methods that were not valid/sane to use publically
     - Event callbacks (ie. checkResize changed to resizeWindow) renamed for meaning
   - Changed some INTERNAL semantics to better align with usage
     - eg. `check*` methods separated from response-to-check
ScaleManager - documentation updates
ScaleManager - IE11 & Fullscreen error updates

- Added prefixed event handlers for IE; it still doesn't work in IE, but that is for other reasons
- Added monitoring of the fullscreenerror event, exposed as a fullScreenFailed signal
- Added `supportsFullScreen` a read-only flag that indicates that this ScaleManager even attempts to support such
ScaleManager - backport for API compatibility

- "Backported" some changed API, all marked as @deprecated
- Minor regression fix for `supportsFullScreen`.
ScaleManager - minor fullscreenerror fixes

- IE9 compatibility (no setWindow arguments)
- And removed code that assumpted event.target was the canvas..
Click Trampolines - support to trampoline pointer events into 'click' events

- This is needed to support Fullscreen on IE11 because IE only trusts 'click' events for this operation; click trampolines as a general solution, although they are only required in some "special" cases.
Pointer - minor documentation update for click trampolines
ScaleManager - minor fullscreenerror fixes

- IE9 compatibility (no setWindow arguments)
- And removed code that assumpted event.target was the canvas..

(Actually adding the changes this time..)
Pointe - removed extra whitespace
Input - Minor Pointer refactor and documentation updates

- `pointerN` are aliases to backed `pointers[N-1]` array.
  This simplifies (and increases the efficiency of) looping through all the pointers when applicable; also eliminates pointer-existance checks
  Removes various hard-coded limits (added MAX_POINTERS); changed `maxPointers` default
- Removed some special-casing from cases where it did not matter
- Removed `=== false/true`, `==` usage for consistency, changed missing value check to `typeof`, etc.
- Updated documentation for specificty; added `@public\@protected`
- `@deprecated` currentPointers due to odd set pattern; `totalCurrentPointers` is more appropriate.
The Gamepad.addCallbacks context parameter was never actually remembered, causing the callbacks to run in the wrong context (thanks @englercj #1285)
Animation.setFrame used the wrong frames array if `useLocalFrameIndex` was `false` and a numeric frame ID was given (thanks @Skeptron #1284)
readme update
docs fix.
Merge pull request #1257 from pnstickne/wip-1191

Input "enabled/disabled" API and documentation consistency updates
All of the Input classes now use the more consistent `enabled` property instead of `disabled`. I.e. you can now check `if (input.mouse.enabled)` rather than `if (!input.mouse.disabled)`. The disabled property has been moved to a getter for backwards compatibility but is deprecated and will be removed in a future version (thanks @pnstickne #1257)
Merge pull request #1282 from pnstickne/wip-trampoline-click

Click Trampolines - support to trampoline pointer events into 'click' events
Pointer.addClickTrampoline now adds in support for click trampolines. These  raise pointer events into click events, which are required internally for a few edge cases like IE11 full screen mode support, but are also useful if you know you specifically need a DOM click event from a pointer (thanks @pnstickne #1282)