[BioPython] Deprecating Bio.Mindy and Martel

[Peter]

Dear all,

As of Biopython release 1.48, Martel and Bio.Mindy are officially
considered to be obsolete.  These modules provided a regular
expression based parsing framework originally used in several of the
Biopython parsers, but required the external dependency mxTextTools.
None of current parsers in Biopython use Martel and Bio.Mindy anymore.

I would like to deprecate Martel and Bio.Mindy (and closely associated
support modules) for the next release.  This means the code will still
be present and functional, but using it will trigger a warning
message.  We can then remove them in a future release.

This change should not affect the vast majority of Biopython users.
However, if there are any Biopython users on the mailing list who are
using Martel and Bio.Mindy in their own parsers, please get in touch.

Thank you,

Peter