BUG: #3029 use 'setlocale' to force C over native language

It turns out that it is not enough to set Qt's locale and we must
also set the c standard library locale in order to avoid data
corruption when the decimalpoint is not period.

Many thanks to Marine Clogenson of EPFL for noticing and helping
figure out how to reproduce this issue!

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22082 3bd1e089-480b-0410-8dfb-8563597acbee