Packaging changes:
* Switch from autoconf to cmake.
Fixes error
checking for guile-config... guile-config
sh: =~: unknown operand
./configure: ./configure.lineno: line 8057: syntax error: bad substitution
that appared with the new version.
* Also add new dependencies for new features: git, python
* (fixes all "missing" errors in cmake's output)
* Stay at Qt4 for now to not introduce too many changes
* Upgrading to Qt5 in the future is feasible (#33248); it builds
* I'm not doing it here because Qt5 apps apparently don't run yet on non-NixOS
b69542ae15