C++ implementation of gmx rms as trajectoryAnalysis module

A modern c++17 implementation of old C-style gmx rms which is using new c++17 fit libraries and have some old bugs fixed.

So far this is done:

• multiple groups for calculations are supported
• -what "rmsd" and "rho" methods seems to work as original (with 10^(-6) difference)
• -prev for dynamic reference
• -mir and -a options work properly (-a does not work properly in the original when multiple groups are selected)
• -mw for mass weights

Potentially todo:

• -what "rhosc" method
• -m, -bm, -bin options (not sure how they are supposed to work, original seems to ignore them)
• -f2 for 2 trajectory comparisons (probably not possible with trajectoryAnalysis module)

Signed-off-by: Alexey Shvetsov alexxyum@gmail.com

Signed-off-by: Titov Anatolii wapukcobaka@gmail.com