Define ghost members and functions for exachange
Remove some waitall statuses
Tweak existing ghost code
Move p4est_add_ghost_to_buf down in file
Populate ghost mirror data
Require contiguous data for ghost exchange
Implement ghost exchange function
Write test for ghost exchange
The ghost exchange seems to work
Merge remote-tracking branch 'github/wrap' into cbdev
Merge remote-tracking branch 'ices/ghost2' into cbdev