spearmint: Check number of bsp surface vertexes on load

Error on load if bsp surface has too many vertexes instead of when it's drawn.
This is already done for models.
spearmint: Clear viewangles on level change

cl is cleared before parsing gamestate. Move viewangles back to cl like in ioq3.

This also fixes a issue in debug builds where sometimes I'm unable to turn the view
after idlogo cinematic plays. Zero frame msec causes divide by zero in CL_KeyState
resulting in viewangles being NaNs and not able to be changed using -= or +=.