do not let users add null inputprocessors to multiplexer
Merge pull request #2158 from jrenner/master

do not let users add null inputprocessors to multiplexer
ShapeRenderer refactoring, added setAutoShapeTypes, more drawing uses current type even if not ideal.

#2011
Merge remote-tracking branch 'origin/master'
Added isDrawing, removed javadoc for methods javadoced in Batch interface.
Correctly #define specularTextureFlag
closes #2159
Merge remote-tracking branch 'origin/master'
Fixed isDrawing.
Added set instead of reusing begin for changing the type. Added scale to rect methods.
Refactoring debug rendering again, now with ShapeRenderer and local coords.

#2011
Stage debug cleanup.