[fp/r42741] Lost commit from 9.x
[ENH] files plugin: Allow plugin to show users file gallery. Use {files galleryId="{{user}}"} syntax to show current user's files
(also fixed $filegallib->get_user_file_gallery() to be able to find other users' galleries)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@46930 b456876b-0849-0410-b77d-98878d47e9d5
[MRG] Automatic merge, branches/11.x 46879 to 46930

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@46932 b456876b-0849-0410-b77d-98878d47e9d5