new: icon for login and error message.
mod: Options UI
mod: merge changes from v12.12 (bug-fix-12 branch)
mod: merge changes from v12.13 (bug-fix-13 branch)
upd: removed invalid entries
upd: version to 15.13
upd: changelog for v15.13
new: v15.13 extension pack
Merge branch 'bug-fix-4'