pathlib.Path can no be used in menpo.io
adds constrain_to_landmarks on BooleanImage
Merge pull request #440 from jabooth/iop

pathlib.Path can no be used in menpo.io
Merge pull request #441 from jabooth/booleanconstrain

adds constrain_to_landmarks on BooleanImage
Merge remote-tracking branch 'upstream/master' into warp_to_mask

Conflicts:
	menpo/image/boolean.py