graphics/xmedcon: update to 0.16.1

While here:

• Add USES=gnome localbase and USE_GNOME=gtk20 to simplify flags
• Reorder some variables

ChangeLog: http://xmedcon.sourceforge.net//Main/New

• patch with several spelling corrections ; updating to recent libtools
• improved homebrew file
• allow reading InterFile dialects without "END OF INTERFILE"
• basic Siemens Interfile support

Reported by: portscout