Needed a bit of twisting in generic private func behind the imm_draw_circle
helpers, but think it's fine.
Note that this demonstrate yet another downside of new dashed shader
compared to olde line style: not only does it needs more complex setup,
and can only work with PRIM_LINES type of primitives, but it also
behaves totally wrong with chained short segments!
We really need to find a better way to do this effect at some point. :(
See intern/gawain for the API change. Other files are updated to use the new name. Also updated every call site to the recommended style:
unsigned int foo = VertexFormat_add_attrib(format, "foo", COMP_ ... )
