relax SVN archive

Finished off the C module compilation testing script.

Added a script for testing out the C module compilation on multiple python targets.

The relax_fit specific analysis module now supports both Python 2 and 3.

The command used was:
2to3 -w specific_fns/relax_fit.py

The relaxation curve-fitting C module now supports compilation on both Python 2 and 3.

First attempt at making the relaxation curve-fitting C module Python 3 compatible.

Python 3 bug fix for the internal PDB and XYZ 3D structure readers by using relax_io.readlines().

Created the relax_io.readlines method for handling the bz2 and gzip module byte strings in Python 3.

The bz2.BZ2File and gzip.GzipFile classes now return lists of bytes strings from their readlines()
methods in Python 3. This causes failures all over relax. This behaviour is probably a bug in
these classes. The relax_io.readlines method is a workaround for this problem, to have a list of
standard strings returned.

Fix for bug #20213 (https://gna.org/bugs/?20213).

The problem was that the generic_fns.sequence.generate() function was searching for a spin based on
its spin ID generated from the spin name and not spin number. Hence two spins with the same name
but different numbers were treated as the same spin, and only data from one was being generated via
the copy() function.

Created the simple Sequence.test_sequence_copy() system test to catch bug #20213.

https://gna.org/bugs/?20213.

The Mf.test_bug_20213_asn_sidechain() system test now uses a temporary directory for output.