[#141] Refactor 'dist' make target

Created by: elbenfreund

This PR improves or Makefile by providing several new targets to collect and compile relevant files in a temporary build directory. The dist target has been fixed so it now creates a valid archive with the extension as its root.

This PR also moves all non code to a dedicated data directory in order to tidy things up further. The aforementioned collect target is responsible of gathering the individual bits as part of the build process.

Closes: #141 (closed)