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.
Split the introduction into separate chapters, add filler documentation for async functions, fix mismatched function arguments.
And remove the autotools. Faster, cleaner. https://bugs.freedesktop.org/show_bug.cgi?id=106514