[INTERNAL] cleaned up EditorManager

Removed dead methods, removed useless this pointers, and deprecated
getRemoteManager method as it will be soon removed.

Change-Id: I412d9c96899eeb906c9f37f29036bb66f04d8e22
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1858
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>