Lyndon Brown authored May 05, 2021 and Jean-Baptiste Kempf committed May 10, 2021

 - offsets can be used for both absolute and relative positioning (except
   offsetting from center).
 - the `i_pos` attribute holds indication of absolute mode, not just
   relative, which was incorrectly stated in marq and rss. (note that
   logo and bargraph have an `i_absolute` attribute, but this is actually
   unneeded and can be removed later).

labels are synchronised across plugins to reduce translator burden and
improve consistency.