Fixes mdbloice#209 mask issue.

Fixes mdbloice#205 mask discrepancy bug.

Fixes mdbloice#188 (random distortion mask bug).

Fix for status() function TypeError.

Added ability to specify pixel value for padding, bug fixes, official…

… support for Python 3.3 dropped.

Multiple mask/image augmentation features added.

Version bump for small bugfixes and various issues.

Multi-threaded image processing added.

Ground truth augmentation capability added.

Optimised skew operation performance (see PR mdbloice#57).