Fix two constants in GLSL shaders. Remove f suffix from float and fix
int to float assignment. They were causing shader compile errors in
OpenGL ES 2 context.
Remove disabling clip plane. Clip plane is unused and never enabled in
the opengl2 renderer. Remove disabling it to avoid causing a GL error
when using OpenGL 3.2 core profile or OpenGL ES.
Make VAO cache vertex stride be size of srfVert_t since that is what
is uploaded to the GPU. No behavior change. There is a disabled debug
id in srfVert_t though which if enabled changes srfVert_t size.
Reserve space for end of list and swap buffer commands. These are absolutely
required and cannot be dropped. Dropping swap buffer command causes screen
to not update and possible crash from drawsurf buffer overflow if not enough
cmd buffer space for many continous frames.
