TODO
- Use BCP-47 naming scheme for fpdf.conf, and drop name vs language tag, and just use tag
	+ the tests pretend we're in bcp-47 mode and convert the current old-school ones
	to bcp47 for the moment
- Improve error handling and reporting.
- Speed optimizations. Some speed might be gained by comparing
  the unknown fingerprint to all known fingerprints at once.