TilemapLayer
- Added "delta scroll rendering"
- Enabled (by default) via `renderSettings.enableScrollDelta`
- Dramatic CPU reduction: 30% to 2% scrolling 50x37 region
- Side-effect: fixed some Chrome de-opt issues with `render`
- Various rendering updates and removal of many `_mc` field
- Made `index` a read-only propert that reflects the layer.index
- Creates a local cache from tile index -> tileset, added `resetTilesetCache`
- Also prevents crash when an index not associated with a tileset is
used; see `missingImageOverfill`.
- Various debug options moved to `debugSettings` and simplified; documentation updated.
- Uses `debugSettings.missingImageOverfill` and `tileColor` (deprecated) to display invalid tileset images
- Only change the context alpha when the tile alpha changes; in Chrome 38
this removed a .5% penalty
- Added `renderSettings` which controls misc. rendering/optimizations.
- Updated documentation to @member, clarified
Tileset
- Added `containsTileIndex` method to allow being queried if the specific tile index is handled/supported.
- Uses a firstgid bias and interlacing to fit the data in single densely packed array.
- Updated documentation to @member, clarified
Loads of updates across most the Tilemap files. Not finished yet, still CSV loading to do and a multi-tileset issue to resolve, but it's a lot more flexible now.
