New features since v1.7.5

Automated testing migrated from Travis to GitHub Actions.
Still needs the following for completeness:
EITHER putting the OE license back, OR changing the little remaining functionality that requires it over to SDF (should be possible now that OFFTK supports partial-charges-in-SDF). I'd think that the latter is a better choice since it will remove the need for an OE license in CI and will let @leeping allow PRs from forks.
Re-enabling Py27 tests (I'm mostly okay with letting this go)
Re-establishing double precision GROMACS builds

This script automates the process of identifying spurious energy minima in an optimized MM force field.

The existing structures in the AbInitio targets are energy-minimized using the force field.
QM single point calculations are performed on the energy minimized structures (includes script to write Psi4 input files).
Results of QM calculations are processed into a new AbInitio target.
Running ForceBalance using this new target will include the energy data on these new MM minima, allowing spurious minima to be removed.

For OpenMM force fields containing Drude particle degrees of freedom, ForceBalance will ask OpenMM to energy-minimize the positions of Drude particles prior to evaluating properties.
Includes an example under 026_drude_water .

Minor changes