the Mesh object can be part of each Layer (at least currently).
also reworked the Mesh code a bit to make it easier to access
the vertex data.
Change-Id: I0490851ba898f0aa2e55b62958dcd8bdb535e98b
this is the first step to add support for GLES 2.x, this
change breaks the dependency of SF on GLES 1.x by moving
all operation into their own class.
Bug: 8679321
Change-Id: I0d2741eca2cefe67dfd9cf837cac10c4d126928b