The behaviour of $tab sole-effects lacked a 'tab' key, so Soto wasn't
catching or writing them to the screen. This commit amends both the
handler and the sole-effect to fix that behaviour.
The keypress handler would check if backspace was past position 0
before deleting one character at that position. If you were at position
0, then it would drop down to the 'else' and send the key value as a
string, throwing off the state between front and back end. This commit
fixes the issue, ignoring Backspace at position 0.
Since Soto is the name of the relay, its location in Landscape should be
the application it relays to: Dojo. This commit amends the mount paths
and source paths accordingly.
