Added GenerateDirections, FindShPeaks, Directions2Amplitude interfaces
wrapping gendir, find_SH_peaks and dir2amp mrtrix commands.

Also fixed issues with out_filename argument for all interfaces
Updated new mrtrix interfaces to new out_file format
updated CHANGES log
added dummy files for testing new mrtrix interfaces
autogenerated tests
fixed possible values for -datatype parameter of tracks2prob interface.
Previous values were in error. correct values obtained from:
http://www.brain.org.au/software/mrtrix/general/formats.html#datatypes
Merge remote-tracking branch 'origin/pr/739'

Conflicts:
	CHANGES
Fixed test files import.