Ok, here is my suggestion: If you're interested, take the upp-nightly and upp-git packages and bring them up to date with current AUR guidelines. Feel free to contact me via PM or email (or in person, I see you're from Prague too ) if you want to discuss how the building/packaging works. When those packages are in good shape, you can take over the stable branch and modernize it as well. For now, I have updated the stable to 2017.1, so there is no rush.

I used to have scripts to publish the nightly packages too. (Yes, I did that one too, but it got lost during migration from AUR3 to AUR4. Fusion809 created them afresh later and I totally forgot about it in my previous post.) Most of the time the scripts worked, but it always took me way too long to notice when something broke. So my tip for you would be to think about some kind of monitoring

Theide.install can be dropped, since pacman hooks run 'update-desktop-database' automatically. The GCC.bm is not used during build. It is present in the package to be installed as a default build method for theide/umk. It would be actually much better if it could be generated automatically during build or even during installation (to make sure that the paths and settings are correct for the final user). Also, it would be nice to generate similar file for Clang. Amrein already did something like that for RPM packages, you can have a look in uppbox/Scripts - it also contains many other interesting things, e.g. the script which builds the tarball.