A few other changes merged:
NEW FEATURES:
- dm._flat_command can be set to point to a dm command vector that will
  be subtracted from the command before they are applied to the
  dm (in comp_dm_shape())
- dm.ifunrot is the rotation angle of influence functions. Does not
  work when dm.elt=1
- set go_quiet=1 to suppress performance printouts in go()
- exact ordering of WFS can be modified using wfs._reordervec (ptr) to
  better match real world systems

BUG FIXES:
- check_parameters() now obeys sim.verbose settings
- typo in extern for wfsMesHistory in reset()
- python env now called explicitely as python2
- fixed typo in cub definition when yflip=1 in make_pzt_dm() functions