Add support for <table> being re-written as TS and TE pairs, <a> links re-written as Lk, and a few other niceties. The code has been broken down a bit, refactored, and also run through more AFL, UBSAN/ASAN, etc.

sqlite2mdoc has been stable for quite a while. This release updates the tool to handle the newst versions of the SQLite header, along with some bug-fixes found by extensive use of AFL.