COLLIMAT: Correctly initialize particle arrays & input checking:
COLLIMAT: Correctly initialize particle arrays & input checking:

- Now COLL input block is checking that the number of particles generated will fit in the allocated arrays (maxn=20000)
- Fixed serious bug in particle array initialization, which incorrectly initialized rvv(1<=particle_idx<=napx<=64) in collimation
- General cleanup

SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack