First cut at allowing velocity as part of position.
Merge remote-tracking branch 'origin/master' into velocity
Merge branch 'master' into velocity

Conflicts:
	DotNet/CesiumLanguageWriter/Generated/PacketCesiumWriter.cs
	DotNet/CesiumLanguageWriter/Generated/PositionCesiumWriter.cs
	Java/CesiumLanguageWriter/translatedSrc/cesiumlanguagewriter/PacketCesiumWriter.java
	Java/CesiumLanguageWriter/translatedSrc/cesiumlanguagewriter/PositionCesiumWriter.java
	Schema/Position.jsonschema
Merge pull request #67 from AnalyticalGraphicsInc/velocity

Velocity support