[ENH] img zoom: Add a pref for jquery.zoom.js and a new 'thumb' mode "zoom" where zoom works in a more conventional way

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@49707 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] comments: Stop code-mirror interfering with comments textarea preventing comment edits to be saved sometimes (thanks Xavi, should fix wish5021)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@49709 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] After inspection, comments lib is not used at all here, might resolve issue #5095

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@49710 b456876b-0849-0410-b77d-98878d47e9d5