Update build-time dependencies and remove remainders of wxPython support
Created by: aimylios
As wxPython support is currently broken, I suggest to remove all traces of the previous effort to bring it back with the help of the (now obsolete) GTK2 compatibility package. It can be re-enabled as soon as the port of KiCad to GTK3 is finished. This is one of the goals for KiCad 5.1.
The second patch updates the build-time dependencies. The removal of dblatex (based on https://github.com/KiCad/kicad-doc/pull/612) should speed up the build process significantly.
As a side effect, these changes make the nightly SPEC more similar to the upstream SPEC.