Fix potential freeze when unloading "import from internet" dialog
Add failsafe for uninitialized translation

For some reason, this was giving me trouble on a fresh Win 8 install.
Tons of high-DPI fixes for UI images

Testing on a 2560x1600 screen has exposed a host of high-DPI issues.  In
addition, Windows 8.1's new 200% DPI setting also has some quirks that
need revisiting, and I'll get to those soon.

As for this commit - the goal is to solve the problem of "tiny images"
in menus, command buttons, and other UI elements while on high-DPI
settings.  GDI+ is now used to resize images dynamically to match the
current DPI setting.  The result will always be blurred slightly (no way
around that), but at least the images will no longer look bizarrely tiny
compared to the surrounding text.

Note that I still need to double-check these changes on a conventional
100% DPI setup!