[FIX] trackers: handleClone action for user selector fields, set to current user when cloning items if autoassign is used so the current user becomes the owner or modifier (only used by customised sites, e.g. cartograf)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52258 b456876b-0849-0410-b77d-98878d47e9d5
[ENH] categories: Add new param hideEmpty to categories module to avoid showing empty categories

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52259 b456876b-0849-0410-b77d-98878d47e9d5