New metatags, fixes various PostgreSQL errors & misc tweaks.

- few minor speed tweaks to build_thumb_html
	- Nothing major, but this is called a fair amount so any speed improvements is nice.
- [.*]tags metatag for tag_categories
	- "artisttags:0" would return all posts with an artist tag.
	- "charactertags:>3" would return all posts with more than 3 character tags.
- order[=|:]random_#### metatag
	- This uses a set seed to generate a random list.
	- jQuery will auto-append a random seed when searching order:random without a seed.
	- This could possibly replace the current random_list ext?
- fixed strict standard errors on futaba/lite themes
- updated links/date in footer text
- tweaked autocomplete
	- /api/internal/tag_list/complete limit is now optional, this fixes issues with the autocomplete not working properly when the original search query has too many possible results.
	- The above list is cached, so removed the delay entirely + minChars = 1.
	- First autocomplete tag is now selected by default. This should be fine due to autocomplete only being used in the search anyway.
	- Tab can be used instead of enter when selecting a tag.
	- Anything autocompleted will now be followed by space.
- fixed various postgresql errors
	- DATETIME has been replaced with SCORE_DATETIME where possible.
		- fixes #354
	- The ext column is now varchar (on postgresql only).
		- This is to fix an issue where CHAR columns return the trailing whitespace on PostgreSQL, but not MySQL/SQLite. Caused things like images on post/view to not appear (or the block to even be created).
	- Forum ext properly uses $database->get_last_insert_id rather than trying to get it itself.