Remove leading underscore for procrustes_results

The string the code was checking was '_procrustes_results.txt' and there
are times where the filename is only 'procrustes_results.txt' causing a
problem when a file with that name was found.

Additional changes that took place in this commit:
    - Broke strings to make the description of --number_of_segments 80
      columns.
    - Remove some un-used imports from the interface.
    - Corrected the documentation for -b
Change assertion message to be 80 columns long
Fix bug where custom axes & comparisons would fail

The coordinates appended a suffix to each of the sample identifiers
depending of which replicate it was (i. e. for the first set of
coordinates the appended string will be '_0', for the second set it
would be '_1', etc ...) processing, hence when trying to match the
sample identifiers to the ones found in the mapping file, it would fail
as there would be no exact matches. A mismatching of this nature would
cause an exception with the following message:
    ValueError: concatenation of zero-length sequences is impossible

Also fixed a typo in a command.
Merge pull request #202 from ElDeveloper/procrustes_issues

Procrustes issues.