Misc. small changes:
1. Fixed small bug in mincAverageDisp atom that incorrectly passed and set logFile.
2. Changed name of xfminvert output files to contain _inverted instead of _inverse. This is explicitly so that the _inverse xfm generated by mincANTS is not overwritten until Issue #81 is appropriately implemented. See also my latest comment on Issue #47.
3. Fixed location of logFile for averge_inv_pure_displacement.mnc. This code is a prime example of where and why a third file handling class (e.g. Issue #68) might be needed.