Use matrix coordinates to name PCB switches

[hrw]

Generated PCB uses names like SW1 - SWxx (where xx == amount of keys) for switches.
Keyboards can have non-standard matrix setup it would be nice to have switches named with coordinates.

Names like SW0_0, SW1_17, SW6_5 would make it easier to find each key.

For example my keyboard has Escape key in top-left corner but it has 5,2 coordinates in the matrix.

[adamws]

Implementation must not break handling of alternative layouts keys:

i.e. some other naming scheme must be used for them when matrix-coordinates used for naming regular switches. Something like SW0_0_1...