Decide a key for sending Ctrl

[arturo182]

Ctrl is useful for PCs, especially over USB

[DJFliX]

Hey! Thanks for this awesome project! I am enjoying this keyboard to the max!
Having a control key is one of the first things I added to your firmware and I think making it part of the "stock" firmware for the BBQ20 would be a very valuable addition.

In my case I decided that the "start call" button (KEY_BTN_LEFT1) would be a suitable candidate: it can not be accidentally pressed, and the placement allows pressing most other buttons without covering them (like the sym button does with the m and the alt button does with the a, s, z depending on your finger size and placement). Not sure if this makes sense for others, but I decided I'd just share my 2 cents.

[grymoire]

Here's my update. I mapped the SYM to Control, and used the top 4 buttons + sym/alt/Uppercase to get the missing characters
https://github.com/grymoire/i2c_puppet-Linux