Squashed commit of the following:

commit 8fd90a3d
Merge: 92bc3a58 be195b76
Author: Boudewijn Rempt <boud@valdyas.org>
Date:   Sun Sep 22 22:22:47 2013 +0200

    Merge remote-tracking branch 'origin/master' into krita-opengl2-rempt

commit 92bc3a58
Author: Sven Langkamp <sven.langkamp@gmail.com>
Date:   Sun Sep 22 15:16:26 2013 +0200

    Workaround for flickering in OpenGL 2 canvas on AMD graphic cards
    BUG:322808
    REVIEW:112883

commit 8c5ec1b0
Merge: 94287d69 ec9b97a5
Author: Boudewijn Rempt <boud@valdyas.org>
Date:   Fri Sep 20 08:52:16 2013 +0200

    Merge branch 'master' into krita-opengl2-rempt

    Conflicts:
    	krita/ui/tool/kis_tool_freehand.cc

commit 94287d69
Merge: 83f300d5 4c7b0a93
Author: Boudewijn Rempt <boud@valdyas.org>
Date:   Thu Sep 19 15:55:36 2013 +0200

    Merge branch 'master' into krita-opengl2-rempt

commit 83f300d5
M...