Fixed up arrow key move for Mathtex Images
Merge branch 'master' into addpoppler
Merge branch 'addpoppler' into glib_new
Fixes #87

The layer is left to delete elements added using AddUndoAction.
Made AddUndoAction undo more descriptive
Hopefully this finally fixes #79
Merge branch 'master' into addpoppler
Merge branch 'addpoppler' into glib_new