Misc tweaks/fixes 2 (fixes #349)

Re-opening pull request on the develop branch.

* Updated JS libs (+ updated existing JS to support updated libs)
* Removed lazyload lib (No longer used.)
* Lowered delay/minchars for autocomplete. (Autocomplete results are cached so there isn't much reason for a high limit)
* Beta exts are now properly prefexed with [Beta] rather than suffixed.
* Hellban ext is no longer forced + has [Beta] tag. (I'm assuming this is a "work in progress" as it is very minimal, lacked info block & most of it is built into the user ext. Also see: [history](https://github.com/shish/shimmie2/commits/master/ext/hellban/main.php).)
* Database Dump should work now for passwordless databases.
* Download All Images should work properly now.
* Reset Image Ids now properly changes IDs on all possible tables, instead of tables in preset list.
* Arrow Navigation ext now uses jQuery (This should fix any problems with browser compatability, see #349)