relax SVN archive

Added the missing import of the open_write_file() function.

Wrote the count_spins() function.

Added the import for the count_spins() function.

Fixes for the write() function.

The display() function now works (although not fully).

Removed the import of the now non-existant Sequence class.

Converted the load_PDB_sequence() class method to a module function.

Converted the write() class method to a module function.

Converted the diplay() class method to a module function.

Removed the now useless methods of the generic_fns.sequence.Sequence class.