Remove unused figures from share/html/

Some of the flowchart images are also unused, but left them there for
completeness.

Change-Id: Ia47f9ac62f865f60c6f1998f407d62c9ba6c66f2
Convert gmx_residuetype_t to a non-pointer

This uses the agreed format for forward declarations in #1490.
This removes the need to include residuetypes.h in any headers, and can
serve as a simple demonstration of the concept.

Change-Id: Ia82d4f96a1ea97e97e11e9840563f8beebe268c8
Merge branch 'master' of https://github.com/gromacs/gromacs