feat: added shortcut key for deleting guides

[Afterdie]

Pressing the esc key deletes the guide that is being hovered on. smol shortcut should come in handy

[ice0]

Hi, Akshat!

Can you record a short video showing the process?
I just checked and the guide is not removed after pressing Esc key.
If I press Esc multiple times, Synfig crashes.

P.S.
Ok, got it. The guide is removed, but the window is not redrawn (unless you move the mouse).

[Afterdie]

@ice0 added a redraw event should be working as expected now 👍

[ice0]

@ice0 added a redraw event should be working as expected now 👍

Now it's better, but it still crashes if I press Esc second time.

fine

[ice0]

Looks much better, but I noticed two more issues.

1. The guide is not deleted if the user pressed the Esc key immediately after the guide was created.
2. Maybe update the current guide after deleting the current one?
   In the example below, after removing the horizontal guide, the vertical guide is not selected until the user moves the mouse.

guide_issues.mp4

[Afterdie]

Looks much better, but I noticed two more issues.

1. The guide is not deleted if the user pressed the Esc key immediately after the guide was created.
2. Maybe update the current guide after deleting the current one?
   In the example below, after removing the horizontal guide, the vertical guide is not selected until the user moves the mouse.

guide_issues.mp4

fixed both the issues. Im not sure if it the queue_draw() is in the right place tho 🤔