Have text cursor change on overtype mode

[willmruzek]

It would be a nice enhancement to have the text cursor switch from | to _ when key entry is in overtype mode.

This would allow developers to easily know when either insert or overtype mode is selected.

[gruehle]

Thanks for the suggestion. In addition to changing the cursor, it may be a good idea to add something to the status bar.

Marking move to backlog.

[njx]

Added to backlog as https://trello.com/c/2ddpNVa0/971-ui-feedback-for-overwrite-mode - closing.