Fix "Display character encoding on export" checkbox in prefs
Fix for WebDAV server returning 300 if lastsync but no lastsync.txt

https://forums.zotero.org/discussion/29040/
Fix updating of item type icon when changing types (broken by 6b7fe80)
Fix error when no results from regexp search
Fix #312, Google Books translator fails in Fx Nightly > 4/2

Also remove remnants of old DOM bindings