Remove broken g_dih tool

Per the redmine discussion for #1094, g_dih was broken
due to hardcoded atom names while the documentation
claimed dihedrals were assigned from the topology.
For now it is better to use g_angle and manually define
the dihedrals. We plan to reimplement g_dih from scratch
for 5.0. Fixes #1094.

Change-Id: I57e0614e4d98bb5d4bbb3aaa1d3ba4377a93f988