add --help --version options

depends on previous getopt_long refactor
Merge pull request #1 from petiepooo/master

Open peripheral mappings with O_SYNC flag + --invert

 * Open peripheral mappings with O_SYNC flag
 * Added option --invert for devices that expect an active-low signal
set version to agreed starting value
Merge pull request #3 from petiepooo/helpopt

EnhReq: --help and --version options