This is a rewrite of the core based on GObject and Gio. This commit
breaks the build in a lot of ways, but basic functionality will start
working again with the next commits.
We will not want to install virtual drivers by default, yet they should
be inside the "all" category. So add a new "default" category and also a
separate array for the future virtual drivers.
We shouldn't need to specifically enable debug logging to get useful
data out of a compiled libfprint either, so always enable debugging
output. It will still be switched off at runtime, by default.
There are no parts of libfprint that are so resource intensive that we'd
want to disable logging. This avoids (hopefully rare) cases where
compiled versions of libfprint are distributed with logging completely
disabled, and thus can't be debugged.
