This also provides a config option to override that default. ~/.cache is
a standard location on GNU/Linux machines for cached content. It is also
good to have the cache outside of the git repo in case `git clean -fdx` is
run, which would delete all files in the directory that are not part of the
git repo, including buildserver/cache/
This makes it so that ./makebuildserver will run without any config file,
using the defaults that are embedded in the script itself. This is like
how `fdroid` works.
This host automatically detects which is the closest mirror, then uses that
one. It does so dynamically, so it'll work on machines that move too. Now
that we are pushing more people to run F-Droid build servers, the defaults
should take those use cases into account.
This keeps the numbers of names down to a minimum, and since the config
is placed right next to the script, this keeps tab completion working
nicely when the config file is in place.
The old file name is still supported.
