Add key commands for moving per word

[kronawetter]

This maps Option + Right Arrow to move forward-word and Option + Left Arrow to move backward-word, like in the default key mapping of the macOS Terminal app.

I decided to create separate methods instead of extending handleKeyCommand: as this is not standard behavior of a shell. (similar to the existing Command + K key command for clearing the screen) If it is preferred to extend handleKeyCommand:, I am happy to update this PR accordingly.

[tbodt]

Thanks! The problem with this approach is that in a lot of programs \x1bb and \x1bf don't move between words. iTerm uses \x1b\x1b[C and \x1b\x1b[D which works in some programs but breaks in others, and lets you configure it in the settings. I'm thinking option should work as a modifier to send escape before whatever key you pressed, so then if all else fails option-b and option-f would work.

[kronawetter]

After submitting this PR, I started to realize that there might be some compatibility issues with these hard-coded sequences. I personally only move per words in the bash, where this sequence works just fine.

While I understand that using the Option key as Meta is a feature provided in most terminal applications, I do not like to use this setting as on non-English keyboards the Option key has to be used quite frequently.

Therefore, I tend to implement user-customizable key mappings. Does it currently make sense to do so or do you plan to introduce any changes soon that might require a rework of this functionality?

[tbodt]

User-customizable key mappings would be awesome! And even if I was going to replace the terminal emulator tomorrow, the keyboard handling code would probably stay the same, so go right ahead.

[kronawetter]

So, I’d like to keep this simple for now and similar to the functionality provided by the stock Terminal app on macOS.

Proposed differences from the Terminal app:

• Single profile only
• Only Cursor keys supported
  • For the first version, I'd like to base this on actions triggered by UIKeyCommands only
    • Only arrow and escape keys can be used as UIKeyCommand input
    • It should also be possible to support Num Pad = / * keys, but I don’t have hardware to test this
  • For a later version, some special key inputs could be derived from other sources
    • Backward delete would be easy to support, for example
• Only "Send text" action supported

Would you be okay with these features?

Screenshots of macOS Terminal app, for reference:

[tbodt]

Looks good for a first version. Of course it would also be nice to include that "use option as meta key" checkbox, if that wouldn't be too hard.

[tbodt]

Closing as we now have option->meta mappings, which fulfills the original purpose of this PR.