* Add support for drawing batched 3D lines of arbitrary color and thickness.
* Add draw3dLine lua function.
* Move line texture out of graphics.h into graphics.cpp, also rename it for proper code style.
* Move line texture generation to batching.cpp, create dedicated batching_add_line function and add support for a line with variable thickness at the start and end.
* Use references in the verts loop
* Add bound checks for line widths
* Warn if the Lua script uses invalid widths
This converts all usages of bmpman textures to OpenGL texture arrays.
That means that all frames of an animation are stored in a single OpenGL
texture object and can be accessed at the same time in a single draw
call. This should significantly reduce the overhead of drawing lots of
particles since all particles of a single animation can be drawn with a
single draw call.
This fixes#1169.
Kestrellius