Add plan files for builder itself

[terhorstd]

These changes add the release of Builder to the planfiles. By this it becomes possible to use a temporary Builder download to install Builder itself! (into configured locations, with module-files, etc..)

git clone https://github.com/INM-6/Builder
cd Builder
./build Builder
cd ..
rm -rf Builder

[akorgor]

Looks nice, but could you add some lines in the README on the usage? It's not entirely clear to me which of the steps described there become obsolete with this new bootstrapping mechanism.

[terhorstd]

Bats seems to have broken, needs fixing first. ref. #60

[terhorstd]

was not actually blocked by #60, but instead had unrelated static code style problems. Fixed here so CI passes.