[INTERNAL] moved static methods from EditorManager

Put those two methods into the IEditorAPI interface.

Change-Id: Ia542edaf5f4c4d533cde1424dfe4b75ae21f8dbc
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1853
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>