Improve the readme
Fix Readme links
Readme: Fix twitter link & use markdown for lists
Readme: Remove line break between links
Renaming FlxString to FlxStringUtil.
Merge pull request #501 from Gama11/dev

Move photonstorm classes to more appropriate places
camera setter fix for FlxTextField
Started work on separation of Atlases from rendering core
Calling camera's fill only when it needed - issue #502
Added function to FlxMath to compute the distance between two FlxPoints.
Removing my last change since it was adding already existing functionality.
Fix issue with compiling in FLX_NO_DEBUG mode
Move StarSprite / StarObject back into StarfieldFX, as well as GlitchSprite into GlitchFX, fix var names
Make FlxKongregate flash-only, fix param names
Fix missing import for SfxFader
Remove FlxExtendedSprite dependancy from FlxSlider, move it to flixel.ui again, closes #499, closes #500
Move addons package to flixel-addons repo
Cleanup and improvement of FlxSlider, add FlxMath.getDecimals()
Add "related repos" to readme
Improve readme formatting