sixtracklib/common: Change unit-test to reflect new semantic of using a NS(MemPool)
sixtracklib/common: Change unit-test to reflect new semantic of using a NS(MemPool)

- initial alignment increases the capacity reserved for the buffer -> a buffer always
  allocates N bytes more than necessary to always find an address aligned at N bytes
  within the range of the buffer and with (at least) the required capacity

- odd alignment is now handled using the least common multiple -> there are no more
  "odd" alignments

SixTrack/SixTrackLib,SixTrack/SixTrackLib,SixTrack/SixTrackLib,SixTrack/SixTrackLib