Change __version__ and __copyright__ strings

All files point to the same version and copyright now
Add filtering module and test suite

This module contains functions to remove samples from coordinates data,
which is a non-practical thing to do, hence the warning in the script
interface.
Fix with --ignore_missing_samples & --custom_axes

When passing --ignore_missing_samples and trying to add a custom axis,
the lack of samples in the coords data would make the data in the
mapping file not match the dimensions of the data in the PCoA data.

Change the default value for --add_vectors and change the contition for
the formatting of the footer.

Change __copyright__ string