clean up gui main and fix a png. (#313)

clean up gui main and fix a png. (#313)

* clean up gui main and fix a png.

- fix libpng warning: iCCP: known incorrect sRGB profile
  issue with runit.png with pngcrush.

- fix includes for gui/main.cc, including removal of
  CoreFoundation.h
- use QApplication static methods instead of going directly
  to the underlying QCoreApplication static methods.

 - no path setting in GUI, instead pass the full path to gpsbabel when using QProcess::start.

in formatload.cc xlt() use qt methods to get a char* instead of
resorting to stdlib.  At this point Qt assumes all translate strings
are utf8.  However, the formatload xlt intent doesn't work because
1) MainWindow::LoadLanguage hasn't been called when
   MainWindow::loadFormats is called.
2) the translations don't exist for the format bits from gpsbabel
   that fromatload tries to translate.  I think this was the intent
   of the gpsbabel_*.ts files which are very out of date and no
   longer distributed.