Pack blend index and weight into one ushort per weight.

This reduces memory per vertex for md5 and iqm models by 24 bytes.
Remove unused members of struct vboData_t.
Pack vertex color into four unsigned bytes.

This reduces memory per vertex by 12 bytes.
Use the 4 byte representation for colors when possible

Much of our data starts in this format, and it doesn't make sense to convert it to 4 floats at load time then back to bytes at run time.
Store texure and lightmap colors in 16bit integers.

Also use only one vec4 attribute for both. Saves 4 + 4 bytes
per vertex.
Clean up tangent space calculation code.

We don't need 6 different ways to calculate tangent vectors.
Remove never used text deforms.

I guess they were leftovers from Quake I or II.
Use QTangents to store normals and tangent vectors.

Saves 28 bytes per vertex.
Merge branch 'vertexpack'

Conflicts:
	src/engine/renderer/tr_bsp.cpp
	src/engine/renderer/tr_curve.cpp
	src/engine/renderer/tr_flares.cpp
	src/engine/renderer/tr_local.h
	src/engine/renderer/tr_main.cpp
	src/engine/renderer/tr_model_md3.cpp
	src/engine/renderer/tr_model_md5.cpp
	src/engine/renderer/tr_model_mdc.cpp
	src/engine/renderer/tr_model_psk.cpp
	src/engine/renderer/tr_model_skel.cpp
	src/engine/renderer/tr_sky.cpp
	src/engine/renderer/tr_surface.cpp