Using non-US locale and pyqt4, moving points with mouse may not work

[Joern Ungermann]

There is still some issue with localization support, where the value generated by moving the mouse is wrongly interpreted.

[Joern Ungermann]

For linux, a workaround is to export LANG=en_US.UTF-8 to force US localisation.

[Reimar Bauer]

Make pyqt4 behave more like pyqt5 in QVariant conversion

pyqt5 is able to retrieve the original type from a QVariant object. In pyqt4 one has to manually retrieve it. The current implementation just converts it to a string, which is afterwards converted to a number. In case of moving a point with the mouse, the float was first converted to a QVariant and then to a double using the toString method. This conversion however delivered a US formatted number as string, which afterwards caused problems when converting it back to a float using localization.

The current code prevents this reconversion by accessing directly the float.

Fix issue #255

→ <<cset 922f2a70833f>>