Why?
- QT will switch from qmake to cmake sooner or later.
- autotools are good for unix-ish systems, cmake also for
macOS and Xcode as well as Windows and VS-code
- Cross compiling the windows-binaries on linux
is not very helpful to attract windows-centric
developers.
Also drop qmake's xca.pro
Generate man-page and sphinx sources of commandline arguments
during build by executing xca (xcadoc.cpp).
Generating Version-patchlevel and git hash is now also
OS independent.
