Add option for indexed vertices for buffers to be used with the mesh component.

**Is your feature request related to a problem? Please describe (REQUIRED):**
When working with meshes you often have to deal with a lot of duplicate vertices. For instance for grids and 9-Patch images.
Indexed vertices make it much easier to work with.

**Describe the solution you'd like (REQUIRED):**
Add an option for meshes and buffers to support indexed. Solar2D has a good implementation of it https://docs.coronalabs.com/api/library/display/newMesh.html

**Describe alternatives you've considered (REQUIRED):**
Working with non-indexed vertices is possible, but more tedious.