Merge pull request #32 from racarone/master

Context and OpenGL State Cache Fixes
added 'color' property to SPButton
Merge pull request #33 from racarone/master

Misc Readability Changes
fixed small typo
remove redundant semicolon
Merge pull request #35 from yandere/patch-1

remove redundant semicolon
Scaffold ported to Swift.
changed behavior of 'SPPoint normalize' when normalizing origin

Now returns default [1, 0] point.
recreated unit-test target to get rid of Xcode warnings about XCTest migration
preventing compiler warning in latest Xcode beta
removed obsolete project setting (caused problems in latest Xcode beta)
Merge branch 'master' of github.com:Gamua/Sparrow-Framework
deleted obsolete file (added by accident)
Merge pull request #36 from dainkaplan/scaffold_swift

Scaffold project ported to Swift
updated some comments
added Swift Barebone project
trying to follow the Apple swift style samples more closely
marked OpenGL state cache as 'experimental' for now, and deactivate it

There was a problem with masking which we couldn't yet reproduce / fix, so I
deactivated this feature for this release. While it's a nice performance plus,
it's not critical to have it deactivated.

More on the issue can be found here:
http://forum.sparrow-framework.org/topic/sxmaskedsprite-appears-before-everything-
added change log for final 2.1 release
added index file to API reference