MacOS package: Added NSHighResolutionCapable tag to Info.plist

With the flag the application will start enable the high resolution
display. I tested this on a Macbook Pro with a High Resolution Display.
The fonts are better to read.

release/Info.plist.in

@@ -6,6 +6,8 @@
 	<string>English</string>
 	<key>CFBundleExecutable</key>
 	<string>TigerVNC Viewer</string>
+	<key>NSHighResolutionCapable</key>
+	<string>True</string>
 	<key>CFBundleGetInfoString</key>
 	<string>@VERSION@, Copyright © 1998-2011 [many holders]</string>
 	<key>CFBundleIconFile</key>