Update docs on the gameResize signal
Typo fix
Adding FlxTypedSignal abstract class, inspired by hxsignals.
Consolidating signals implementation into FlxSignal.hx, moving it back to utils package.
Fixing errors and test suite for FlxSignal.
FlxSignal: renaming isOnce to dispatchOnce for clarity.
Moving FlxSignalTest to flixel.util package.
FlxTypedSpriteGroup: fix initial scale
Merge pull request #973 from gamedevsam/dev

Adding FlxTypedSignal abstract class, inspired by hxsignals.
Added `getFirstJustReleased` to `FlxKeyboard`
Merge branch 'dev' of https://github.com/HaxeFlixel/flixel into dev
Check for button exists.
Fix Tilemap on game resize
Better doc for _helperBuffer
DRY
Minor optimizations
FlxTilemapBuffer cleanup
Minor fixes
Better doc for _helperBuffer
Merge branch 'dev' of https://github.com/HaxeFlixel/flixel into dev