tilp: remove long-dead UsbKernel option from the cables list in the UI.

Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>
tilp: support screenshots for 84+CSE (and pave the way to future models).

This uses the recently added 'pixel_format' field rather than
hard-coding pixel formats in tilp based on the calc model.

Code by Benjamin, translation by Lionel.

Signed-off-by: Benjamin Moody <floppusmaximus@users.sf.net>
Signed-off-by: Lionel Debroux <lionel_debroux@yahoo.fr>