Rename x11/rsibreak-kde4 to x11/rsibreak and update to 0.12.6.

Update to the latest release, which is based on KDE Frameworks 5. Consequently,
rename the port and adjust its dependencies.

KDE users: do not worry, everything works fine in a KDE4 desktop.

Also assign maintainership to kde@, as agreed upon by avg@.

PR: 217710
Approved by: avg (former maintainer)