Double filament sensor

Filament Sensor based on things [Craftbot filament sensor](https://www.thingiverse.com/thing:2537054) and [Filament sensor](https://www.thingiverse.com/thing:2563347). Thanks to them !

First of all, I didn't have any tangle problem yet with good filament spool. I just keep an eye on the ending spool... So boring, and we are always distracted at this critical moment.

Last week, an unexpected issue appeared... Filament wasn't perfectly round somewhere in the spool, I noticed oval 1,75 x 2.02