Attempt to fix a shadow problem, the same as the Mesh Core.

Support for multiple beams per e2, default is 5 and can be changed with the command BeamCore_MaxBeamsPerE2.
Every function can now have an extra parameter at the start to specify the beam group you're drawing to, if you do not specify any, it defaults to group 1.

-> to put a point in group 1 you can do:
beamPoint(1, 1, vec(0,0,0))

-> in group 2 it would be:
beamPoint(2, 1, vec(0,0,0))

groups can NOT interact with eachother, it is not their purpose.
So points in different groups will not link.