Fix #476 Auto-detect language on fresh launch

Freeseer will now try to use the appropriate translation if it exists
for the user's system language. It does this by detecting the user's
locale and searching for a matching translation. The US English
translation will be used if no matching translation exists.
WIP: Fixes #576 High/Low DPI Adapting

The Qt UI would change the size according to the logical DPI of the computer
Only Windows and Linux have been tested. (Should also work on Mac but have not tested).
Test: mixin for dpi adapt classes