Add a desktop file and application icon.

Improve desktop integration by registring application icons and desktop file.

SVG logo info:
source: https://en.wikipedia.org/wiki/File:Mupen64plus.svg
author: Scott 'Tillin9' Knauert
license: Creative Commons Attribution-Share Alike 3.0 Unported

EDIT: please disregard this pull request. Desktop integration should be applied to the console-ui instead. Sorry for the trouble.