Merge branch 'Translation'
added "ply type" property
added 'strain limits' property
added 'stress limits' property
fix
increased minimum size of widget
added preference dialog
implemented mechanism to change language during runtime
allows to change language during runtime
added more categories
Merge branch 'PreferenceDialog'
Merge branch 'master' into Translation
Merge branch 'Translation' of github.com:Negusbuk/MatDB into Translation