Merge remote branches 'praxes_hexrd/master' and 'origin/master'
added share directory and IPython Notebook for SX calibration
Merge remote-tracking branch 'praxes/master'
Merge remote-tracking branch 'praxes/master'
Merge remote-tracking branch 'praxes/master'
Merge remote-tracking branch 'praxes_hexrd/master'

Merge in Darren's recent changes to my clone
implements extract_gvecs
moves extraction code to subpackage