feat: Undo and Redo

[huytd]

Implemented the Undo and Redo feature.

Usage:

• ⌘Z: Undo
• ⌘⇧Z: Redo

https://user-images.githubusercontent.com/613943/226196309-96682237-be3b-4ea0-afc5-3e13e1d79930.mov

Due to the way we handled Text editing tool, every keystroke will be recorded as an Undo step, so, if you type "Hello", there will be 5 undo steps.

For other tools (Rect, Line, Erase, Copy/Paste,...), undo step will be recorded as a whole edit.

Currently, there's no limitation on how much undo steps to be recorded (unlimited history!), it gonna crash when the computer run out of memory, but let's wait and see.

[widcardw]

However, the Eraser tool does not seem to work well. Maybe we should work into it further.

https://github.com/huytd/ascii-d/blob/4b2a184dee9b5d64ee1c5963967e0a5e84d11e41/src/tools/eraser.rs#L33-L48

The problem may result from the cursor event: the function draw is triggered on mouse (pressed) move, so a large amount of states are pushed into one version. A strategy should be implemented so that draw or version push are called only the cursor_position changes.

[huytd]

Ah. good point. Yeah I totally forgot about the fact that draw can be called multiple times on the same cell. Yeah I think your suggestion is the way to go about this. Let me push a fix

[widcardw]

Thanks. I am trying to fix this problem with these changes below

But I've found another problem. If you follow these steps:

• Draw somthing (for example, a rectangle)
• Do some erasing
• Undo the erasing
• Undo (undo drawing the rectangle)
• Draw another rectangle
• Do some erasing
• Undo the erasing

Then you will get this

It seems that there may be some problem with the version stack. Please check it out also, thanks.