Fix marker stretching.

The fitToViewport method applies an actor transform to map the geometery
into the window. This patch adds a transform filter on the glyph source to
correct the aspect ratio of the glyph source data.
got wmo pictures and size ok
Merge branch '553_stretched_markers'
good pix with not-strecthced markers, final tweaks to default sizes
Merge branch '553_stretched_markers'