[Bug] kinesis w/ stapelberg ghosting on certain keys

[rockybulwinkle]

When I press a key in the top row of one of the key wells, and a key in the next row down in a neighboring column, I get ghosting. For example:
2+q => key "1" ghosts
2+e => key "3" ghosts
3+w => key "2" ghosts
3+r => key "4" ghosts

It only happens for me with these sorts of combinations of the top two rows (that I've noticed so far anyway).

It appears the issue is an insufficient delay after unselecting the row in matrix_output_unselect_delay. For my combination of hardware, it seems to need around 20 microseconds in order to get rid of this ghosting, up from the original 10 microseconds.

My keyboard is a kinesis KB600LF.
Stapelberg's kinT v2020-06-30.
Teensy 4.1

My best guess as to why I'm experiencing this, is perhaps the capacitance is a bit higher in either the LF variant of the kinesis KB600, or perhaps it is higher in this older revision of Stapelberg's board.

I've already applied and tested a fix that I will submit a pull request for shortly.

[rockybulwinkle]

Just submitted a pull request. I hope to test my hypothesis of why this is happening this weekend. I'll hook up the lines on my 'scope to see how long the rise/fall times are.