fix problem with clearing non-empty location field after changing type of config variable
introduced by cd9db17 ("clear variable location cell in variable
panel, if variable class or type changed").
Closes #26
To generate message.pot file:
python mki18n.py -p --domain=Beremiz
To generate .mo files for all languages:
python mki18n.py -m --moTarget=../locale --domain=Beremiz
To generate app.fil:
find .. -name "*.py" -exec grep -q '_(' {} ';' -print -o -name "*XSD*" -print -o -name "*.csv" -print | grep -v '/build/' | grep -v '/pyjs/' > app.fil