new rtl naming

- rtl/ltr suffix comes after the -symbolic suffix
- varinats that already have the flipped version are simply symlinked
- oriented icons that lack a flipped version have to have
  a specialcased export filenaming.
flipped camera

- yosef feels like it's pointing in unnatural direction :)
pan-start, pan-end were missing.

- also removed symbolic links to unused text direction icon
  with unfortunate name. Somebody will scream at us eventually.