Add force correlation to AWH module
This change adds the calculation of force correlation statistics
during an AWH biased simulation.
The main quantity of interest is the time-integrated force
correlation, also known as the friction tensor
(see e.g. http://dx.doi.org/10.1103/PhysRevLett.108.190602).
The friction tensor defines a metric on the coordinate space and
the local volume element of this metric is a useful measure for
determining which regions need more or less sampling.
gmx awh prints the friction (tensor) and can also still process
energy files without friction data.
Change-Id: I164be4665004dea5b250e3c7ac135ac1c1cbd783
18 files changed: