made 'QuadBatch.mVertexData' protected, analog to 'Quad' (closes 385)
Merge branch 'master' of github.com:PrimaryFeather/Starling-Framework
added more vertex & quad manipulation methods to QuadBatch
clearing vertex and index vectors in QuadBatch.dispose (closes #390)
added missing 'registerPrograms' call

Without it, some situations could cause 'renderCustom' to be executed without a valid program.