Set basis for further development

See merge request rui.machado/gpi-2!4

Starting point was
indent -bad -bap -bbb -bbo -bl -blf -bls -bli0
       -cli2 -i2 -ip0 -lp -l79 -lc19 -cd0 -nfca
       -nut -sbi2 -sai -saf

with some hand-tuning.

Use GASPI data types

See merge request rui.machado/gpi-2!1

Revert "fix for omnipath: changing gaspi_notification_id from unsigned int to byte length, because omnipath writes single bytes at a time, which can result in races because (a) unexpected notification value is read out (b) zero value after reset is filled, bug fix: restrict the notification value to byte length which can not be overwritten: fix has been tested on Omnipath system at kraken.cerfacs.fr"

This reverts commit 7b65525c.

fix for omnipath: changing gaspi_notification_id from unsigned int to byte length, because omnipath writes single bytes at a time, which can result in races because (a) unexpected notification value is read out (b) zero value after reset is filled, bug fix: restrict the notification value to byte length which can not be overwritten: fix has been tested on Omnipath system at kraken.cerfacs.fr

- compare with value returned by _rw_list_elem_max.
- in debug mode.
- addresses in part #52 (github).

- make segments available locally by setting flag (trans).
- adds test.
- closes #53 (github).

- verify number of ranks before trying to register segment in group.
- modify test to return success when running single instance.