editor prompt: movable cursor

[frizinak]

Gives the user a visual cursor which can be moved with left and right arrow keys.

Which, as you would expect, makes command editing easier and actually viable.

Quick screencast:

cast-160a33fdbba2d8812439504cd2e4ff996ab702fe2a06e59fd839dec9e9fa4d06.mp4

Thanks for the awesome work!

[xinhaoyuan]

Thanks - I like the idea! But implementation wise, I'm debating on whether to reuse awful.prompt or reinvent the wheel of line editing. Will leave this open until I have my answer.