Merge branch 'hbond-cs'

Conflicts:
	xcamshift/src/cython/Cython_shift_calculator.html (removed)
	xcamshift/src/cython/Cython_shift_calculator.pyx
	xcamshift/src/cython/instantiate.hh
	xcamshift/src/cython/setup.py
	xcamshift/src/xcamshift.py
Merge branch 'master' of https://github.com/locsmith/xcamshift.git
ring potential now reports chemical shifts even if there are no rings
present in the system

not the tests with gb3 haven't been carried yet, as they will require
several hours of processing ;-) see a later commit for any changes to
the test suite required because of the presence of zero valued ring
chemical shifts