Add possibility to use CMake to build

[foeroyingur]

This might be "controversial" but this would help make building easier for users (but life more difficult for developers)

[g-mathias]

I''ve been working on a spack package for cpmd (https://github.com/spack/spack), which adds an abstraction layer to the build process. I guess adding cmake on top of gnu make will require quite some effort.

[kloeffelt]

I think talking about changes in the build system at the moment is just to specific. There is a lot where the community needs to align, first of all we should try to get a picture of the community at all:)
@foeroyingur however I don't wont to stop you to develop a cmake build system...

[foeroyingur]

@g-mathias That's great! A spack package is going to be very useful.

@kloeffelt I partly agree. The community needs to come together to get things going.

I think a CMake build can be an addition and not a replacement for the current build process. Adding a basic CMake build would not require too much effort.

[g-mathias]

for the spack package someone was quicker
spack/spack#34705
I just submitted a new pull request
spack/spack#35081