Fix port selector dialog; simplify rig model selection with manufacturer sub-menus

[cjcliffe]

• Rig serial port selector dialog layout errors fixed (cubicsdr0.2.5 on Debian Stretch - Unable to enter serial port  #703)
• Dialog can now be resized
• Rig model menu will group models for each manufacturer into sub-menus if more than one model per manufacturer

[magellan-13016]

Thanks for the work. I've downloaded the 4 new files and compiled CubicSDR Again. Now I can select the port I want but, whatever I choose, the link with my FT-847 failed.

I also need a solution tu use GPredict with CubicSDR to correct the Doppler effect for an educational project with ISS packet radio with 153 students so please give me answer on the forum and help me to solve me tiny problems.

I would like to help testing all the builds before the next stable 0.2.6. Just give-me the links if you want.

Thanks for all, David.

[cjcliffe]

@magellan-13016 Glad to hear port selector confirmed working -- still a short list of issues remain until the 0.2.6 release but in the meantime I'll try spinning up a new AppImage and post it in your #725 issue.