[Replicant] scripts: modem: rework the user interface and other small fixes

[Denis 'GNUtoo' Carikli]

Hi,

In addition to the patch that will follow in a response to
this mail, here's an URL to the see the patch in a web interface:
https://git.replicant.us//contrib/GNUtoo/vendor_replicant-scripts/commit/?id=401c8ed8ef74b90b4cbe1ce7f220219b737504b4

And here's how to get it in a git repository:
git clone https://git.replicant.us//GNUtoo/vendor_replicant-scripts
cd vendor_replicant-scripts
git show 401c8ed8ef74b90b4cbe1ce7f220219b737504b4

Denis.