Some key combinations are not being picked up correctly

I mentioned this bug on the discord this weekend, but found that after updating to v1.0.1 the behavior is slightly different. I am writing the bug as of v1.0.1 below and leaving the earlier bug in case that helps track the issue.

I have found problems with several key chords. Example:

* `Control - Underscore` (`C-_` in emacs parlance) is ignored. This happens with both the software keyboard and an external bluetooth keyboard.
* `Control - <` and `Control - >` (`C-S-,` and `C-S-.`) are ignored by the software keyboard, and detected as either `,` or `.`, respectively, when using an external bluetooth keyboard.
* `Meta - <` is detected correctly with the software keyboard, but `Meta - Shift - ,` is detected as `Meta - b` when using an external bluetooth keyboard.

I am running iSH v1.0.1 on an iPad running iOS 14.1.

Issues from a few days ago, prior to v1.0.1:

> I have found problems with several key chords. Example: `Control - Underscore` (C-_ in emacs parlance) is intercepted as `m' when using the software keyboard. When using an external bluetooth hardware keyboard, the key chord is ignored. (In the case of the ext. keyboard, the chord is Control-Shift-Dash keys.)

Possibly related to [this issue.](https://github.com/ish-app/ish/issues/557)