Bump lmfit support to version 7
The breaking API change means that distributions will not be able to
build GROMACS reliably with support for lmfit of arbitrary versions.
Nor does lmfit provide any support for querying the version.
Updated the FindLmfit and other cmake code to make better use of
modern cmake idioms for managing build targets. lmfit support is now
handled by a tri-state GMX_USE_LMFIT cmake variable, which defaults to
using the bundled version. When building without lmfit support, tools
that call such fitting will now issue a fatal error.
Reorganized aspects of gmx_lmcurve to better encapsulate the
dependency, now that we have to support the absence of lmfit.
Updated install guide and COPYING file.
Refs #2533
Change-Id: I6b14e08be216f803326b0ad9215b8d89bb0962c1
16 files changed: