relax SVN archive

Fix for the dipole_pair.define user function - the interatom object can pre-exist, containing other data.

More refinements of the dipole_pair.define user function definition.

Refinement of the dipole_pair user function definitions.

Created a set of icons for the dipole_pair user functions.

Shifted the relax_data.dipole_pair user function into the new dipole_pair user function class.

This has also been split into two new user functions:
dipole_pair.define used to set up the magnetic dipole-dipole interactions.
dipole_pair.set_dist used to set up the r^-3 averaged interatomic distances.

The relax_data.dipole_pair backend now uses the direct_bond flag.

Added CONECT records to the sphere.pdb file to allow connectivities to be more easily determined.

This is for the internal reader, as the current algorithm for finding attached atoms is distance
based, and as all N atoms of all residues are at [0, 0, 0], this algorithm fails.

Implemented the are_bonded() structural API method for the internal structural object.

Created the structural API base are_bonded() method - this is for determining if 2 atoms are bonded.

This is a method stub which raises a RelaxImplementError.

Started to add the backend of the relax_data.dipole_pair user function.