[wip] net/gmtp, an mtp device browser

Hi,

here's a wip port for gmtp which is a gtk3 gui for mtp devices,cf
https://gmtp.sourceforge.io/usage.html

so far i havent been able to make it list the files on my smartphone,
while mtp-detect sees it and can access files fine.

either running the gui as root via xhost+ or chowning the ugen/usb
devices to my user doesnt seem to work around it.

sending it here so that if someone is interested in the topic can pickup
from there...

Landry