Add support for strip materials.
First cut at changes after review.

Rename lightColor/darkColor to evenColor/oddColor, replace horizontal boolean with enumeration.  Still needs some cleanup.
Minor tweaks.
More doc tweaks.
Merge remote-tracking branch 'origin/master' into stripeMaterial

Conflicts:
	DotNet/CesiumLanguageWriter/CesiumLanguageWriter.csproj
Changes after review.
Merge pull request #61 from AnalyticalGraphicsInc/stripeMaterial

Add support for stripe materials.