MeshBuilder: move vertex transformation (position, normal, color and UV) to the addVertex method so it is applied to all added vertices (required for separation of concerns)
Add Mesh#getIndicies(srcOffset, count, ...), add MeshPartBuilder#addMesh(...), see #2156
Send correct arguments to texSubImage2D

Fixes #2672
Only transform if needed
Merge branch 'master' of https://github.com/libgdx/libgdx
Merge branch 'master' of https://github.com/libgdx/libgdx into migeran