Feature request: keybindings for rebalancing terminals

[Charlie DeTar]

Rebalancing terminal with double-click is great. It would be even better if we could use keybindings to rebalance without reaching for the mouse and precision-locating the pointer over the divider.

The docs (https://terminator-gtk3.readthedocs.io/en/latest/gettingstarted.html) only mention mouse-based methods of executing a rebalance, and the keybindings preference pane has keybindings for resizing, but none (at least as of v1.91) for a proportional rebalance.