Add initial support for 8.3's built in FTS. Based on patch from Ivan Zolotukhin as...

Add initial support for 8.3's built in FTS. Based on patch from Ivan Zolotukhin as part of his Google Summer of Code project, with several fixes/updates from me
to work with the actually committed full-text-search code in PG core. Note in Ivan's version, istm you could map multiple dictionaries for each configuration, but the committed core schema doesn't imply that; we might need to change that later. I also updated the TODO file with some
left over pieces for FTS support.