Enable ColorMatrixFilter function chaining

This allows, e.g.:
new ColorMatrixFilter()
    .adjustHue(h)
    .adjustSaturation(s)
    .adjustBrightness(b);
add return value to ColorMatrixFilter.concatValues
replaced usage of 'requestContext3DMatchingProfiles' with custom implementation

Unfortunately, that AIR method is still buggy. See:
http://forum.starling-framework.org/topic/potential-problem-with-the-starling-profile-auto-selector
and
https://bugbase.adobe.com/index.cfm?event=bug&id=3757050
Merge branch 'master' of github.com:PrimaryFeather/Starling-Framework
fixed missing argument check (closes #541)
fixed that fatal error box was not scaled right in some situations
changed 'reqeustContext3D' call to be backwards compatible again
now handling invalid profiles, too

e.g. "baselineExtended" is only available beginning with AIR 3.7
updated release date
set version to 1.5 in maven pom.xml
updated swc file for 1.5 release
raised version to 1.5.1-SNAPSHOT
exchanged references to HTTPStatusEvent.HTTP_RESPONSE_STATUS with custom constant (closes #545)

This constant is not always available in pure Flash.
raised version to 1.5.1
updated SWC for 1.5.1
updated changelog for 1.5.1
updated maven pom.xml for v1.5.1
starting development on v1.5.2
added 'color' property to the Button class
optimized TextureAtlas.getNames by caching sorted list of names (closes #548)