Fixes particle system

Now all graphics systems use the fallback method. This should
technically be a temporary fix until the original maintainer (forthevin)
fixes all the individual graphics systems.
The fallback actually could be a good thing for all systems as a
permanent solution, because all the systems use sprite batching. This
means all the particles will be using one draw call anyway. But this
needs to be tested.

Also added draw_get_blend_mode* functions. These were actually some of
the functions I wanted for a long time, but never got around to
implementing them. They were needed in the particle system fix.
The way I implemented them kind of sucks though. Maybe someone else has
a better solution?