Refactored subleveleddb to support variable sublevels, as specified by opts. Moved sublevel settings out to metaphone-db-settings.js.
Moved subleveleddb.js out of metaphone directory, as it is not megaphone-specific.
Moved readAllValuesFromSublevel to subleveleddb.js. Moved checkError to its own module.
Added phoneme-based homophonizer (and indexer) that is at parity with the megaphone-based one.