More GLSL code:

More GLSL code:
- use macros to access and modify render inputs bit-field;
- un-alias generic vertex attributes for ARB vertex calls;
- use MAX_VERTEX_PROGRAM_ATTRIBS (NV code) or MAX_VERTEX_ATTRIBS
  (ARB code) in place of VERT_ATTRIB_MAX;
- define VERT_ATTRIB_GENERIC0..15 for un-aliased vertex
  attributes for ARB_vertex_shader;
- fix generic attribute index range check in arbprogparse.c;
- interface GLSL varyings between vertex and fragment shader;
- use 64-bit optimised bitset (bitset.h) for render inputs;