Fix broken .desktop file to comply with FDO specifications.

--- a/bitmeter.desktop
+++ b/bitmeter.desktop
@@ -4,10 +4,10 @@
 Comment=JACK diagnostic tool
 TryExec=bitmeter
 Exec=bitmeter
-Icon=bitmeter.xpm
-Terminal=0
+Icon=bitmeter
+Terminal=false
 Type=Application
 StartupWMClass=Bitmeter
-Categories=Application;Audio;AudioVideo;X-Jack
+Categories=Audio;AudioVideo;X-Jack