Implement remaining chat input handling

[stackotter]

It's easiest to explain this with an example. If you click the up arrow while writing a chat message, the game crashes (because it tries to render an up arrow) whereas it should replace the current text with the previous message that the user sent.

The main tasks are:

• Support up and down arrow keys (to reuse previous messages/commands)
• Support left and right arrow keys (to navigate message input)
• Support using the shift key to highlight text along with the arrow keys
• Support cmd+x to cut the selection and cmd+c to copy the selection
• Support cmd+a to select all of the text
• Support backspacing selections
• Probably more that I haven't thought of yet

Additional:

• The cursor blinking timer should restart every time the cursor moves (instead of purely being based on CFAbsoluteTimeGetCurrent)

[U5KUN]

• Support Japanese and Chinese etc.
• Support _ key

[jmshgs]

• Support Japanese and Chinese etc.

this has more to do with localization and should be in a separate issue

[stackotter]

• Support Japanese and Chinese etc.
• Support _ key

Do you mean supporting the japanese and chinese languages for localisation? or just supporting japanese and chinese characters in chat? (which I thought I fixed, but maybe I didn't)

[stackotter]

GitHub closed the issue automatically when the PR was closed (because the PR referenced the issue), but the PR only addresses part of the issue so I'm reopening.

[stackotter]

• Support Japanese and Chinese etc.
• Support _ key

I've added full unicode support so Japanese and Chinese characters should now work (I tested some hiragana and it seems to be working correctly).

What do you mean by 'support _ key'?

[stackotter]

Another PR closed the issue again, whoops 😅 It completes one of the subtasks not the whole things