Add cmake-based build system

[asl]

This adds cmake-based build system instead of manually written Makefiles. Included benefits:

• Variety of cmake-supported makefile generators (e.g. Ninja or VCPP project files)
• More flexibility in options, targets, etc.
• Automatic generation of compiler database for LSP servers
• Simplified checking of Python presence and resolving of include / libpaths
• ...

It would be trivial to update to the latest pybind11 versions as well (see #216)

PS: Note that VCPP generators will likely not work due to the way compiler options here and there are specified and might be further generalized a bit.

[asl]

I have not updated readme's and github actions for new cmake system – let me know if you would like me to do this.