Use CMake install for install-mdrun (bugs #549, #555)

Use CMake install for install-mdrun (bugs #549, #555)

The custom target install-mdrun now invokes the cmake_install.cmake
script that is generated by CMake to perform the actual installation.
Adds support for DESTDIR and RPATH rewriting (see bug #570).

To implement this, all installation targets are now grouped into
components: "data" for shared data, "development" for headers and
pkgconfig files, "libraries" for libraries needed by mdrun, "mdrun" for
mdrun itself, and "runtime" for other binaries and libraries.  Only
"mdrun" and "libraries" are used at the moment (the latter only when
installing with shared libraries).

Haven't tested this with Visual Studio, but if it doesn't work, it
should be easy to adapt.