Fix typo in validation.
Use math.log instead of np.log for Python longs.
Fix the masking behaviour.
Added function to sample masks from the distribution.
Per example switch for sampled_dropout_average.
More error-checking in exhaustive_dropout_average.
Properly initialize input_scales in exhaustive_dropout_average.
Special case the zero mask in masked_fprop.
Get rid of the np.all() special case that is causing a test failure.
Add dropout_input_mask_value support.
Get rid of duplicated OrderedDict import.
Do proper switching for mask value in masked_fprop.
Rename 'sc' to 'scale', fix scaling in masked_fprop
Scale inside the switch.
Tests for input mask value.
Smoke tests for some keyword args.
Test for exceptions.
Merge pull request #312 from dwf/improve_masked

Improve masked fprop, dropout, etc.