Merge release-4-6 into master

Merge release-4-6 into master

Conflicts:
	CMakeLists.txt
	cmake/gmxCFlags.cmake
	src/gromacs/legacyheaders/rdgroup.h: deleted
	src/kernel/CMakeLists.txt: ignored. Instead renamed main.c to main.cpp
            and added main.cpp to programs/*/CMakeLists.txt
	src/mdlib/CMakeLists.txt: applied to src/gromacs/mdlib/CMakeLists.txt
	src/tools/g_anadock.c: master changes applied to gmx_anadock.c
	src/tools/make_edi.c: master changes applied to gmx_make_edi.c

For 5.0 we always compile with C++ and thus all main functions should be
always compiled with C++. Thus we shouldn't have a main.c which is compiled
with C++ but instead the main function should always be in a cpp file.
Because tools are currenlty anyhow changed to g_ana (Change-Id: Ifcd166dbd)
I don't rename all tools main files to .cpp.

Change-Id: I083968bcbaca8020364f19a69d9a5b74f00b1eac