Remove unused icons after cleaning up Math zoom

After commit ffc2e5be1f712b09710e2096ad2f7eb81b80118d ,
these deleted icons are useless since other UNO commands are used instead:
  View050     -> Zoom50Percent
  View100     -> Zoom100Percent
  View200     -> Zoom200Percent
  Adjust      -> ZoomOptimal
  FitInWindow -> ZoomOptimal

Sorry I forgot to remove then in that commit.

Note: As UNO command now is 'zoomoptimal' instead of 'adjust' and
people feel 'adjust' icon better, I deleted the disliked 'zoomoptimal'
icons and renamed 'adjust' icons to it.

Change-Id: I141f2c4ad2f63928efb15faa5f68bc9c6dabc144
Signed-off-by: Rodolfo Ribeiro Gomes <rodolforg@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/4117
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>