relax SVN archive

Import fix for the OpenDX mapping package, recently broken with the relative import for Python 3 change.

More usage of the is_unicode() function in the generic_fns.mol_res_spin module.

Created the check_types.is_unicode() function for Python 2+3 compatibility.

This is used in the generic_fns.mol_res_spin module.

Another raise() function call to statement change for 2to3 preparations.

Converted some raise() function calls to raise statements in preparation for the 2to3 conversion.

Converted the ScientificPython PDB reader to support both Python 2 and 3.

The command used was:
2to3 extern/scientific_python/IO/PDB.py -w

The __repr__() method was manually modified due to the 'list' variable clashing with the 'list'
type.

Created a new module for simultaneous Python 2 and 3 support in relax called 'compat'.

Python 3 fixes - the list() function is now used in combination with range() to generate the ordered list.

range() in Python 3 is an iterator object (just as xrange was), so now the list() function has to be
called.

Python 3 preparations - mass conversion of all xrange() calls to range().

Fix for a bug introduced at r17624 in the generic_fns.sequence.validate_sequence() function.

The is_none() function call doesn't seem to be working correctly.