Clean up t8_cmesh_partition.c

[chiaraMaHe]

ToDo's

• 249 – unused function? – check first
• 277 – try to work around calling function (log(P) runtime)
• 402 - reactivate T8_ASSERT (*send_last >= 0);
• 681 - inefficient since we copy each tree for itself
• 707 - ??? temp_offset += T8_ADD_PADDING (temp_offset) instead of the last 2 lines?
• 728 – check indentation
• 850 – think about this
• 942 – change padding to sizeof
• Remove the const qualifier at the cmesh_from parameter
• 1348 - assert that proc_recv is still contained in the list of receivers
• 1365 – get ghosts
• 1382 – remove case?
• 1457 - computing recv information needs the shared array of the old partition in cmesh_from
• t8_cmesh_partition - Check whether the input data is consistent
• t8_cmesh_offset_percent - Check that percent is the same on each process
• 1783 - If it does not exists (NULL is returned), we could compute the number of trees and first tree of the next smaller rank by hand
• t8_cmesh_offset_half – test with shared trees