[TASK] Move overlay icons from typo3/gfx to ext:backend

Some unused overlay icons are removed.

icon_fatalerror.gif icon is removed too, the same icon
exists in ext:t3skin

Resolves: #67968
Releases: master
Change-Id: I27a882ff918e96268b910ffd90fd1d96f24ccd52
Reviewed-on: http://review.typo3.org/40975


Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>