Add gesture support

[sile]

This pull request mainly introduces gesture support to the application and makes related changes to several files. The most significant changes include the addition of touch gesture support, modifications to the App and Event structs, the creation of a new gesture.rs file, and updates to the ConfigWidget.

Here are the key changes:

New Features:

• CHANGELOG.md: Added touch gesture support. This includes tap to switch to the picker tool, two-finger tap to switch to the selection tool, swipe to move the camera, two-finger horizontal swipe for undo/redo, and pinch to zoom in/out.

Codebase Modifications:

• src/app.rs: Added a zoom method to the App struct that allows the user to zoom in and out.
• src/event.rs: Modified the Event enum and from_pagurus_event method to handle PointerEvent and GestureEvent. [1] [2]
• src/game.rs: Updated the Game implementation to handle PointerEvent. [1] [2]

New Files:

• src/gesture.rs: Created a new file that defines PointerEvent, EventType, PointerType, GestureEvent, and GestureRecognizer. This file also includes methods for handling different types of touch gestures.

UI Updates:

• src/widget/config.rs: Added a gesture field to the ConfigWidget struct, which is a toggle widget for enabling or disabling gesture support. The widget's layout and event handling methods were updated accordingly. [1] [2] [3] [4] [5] [6] [7]

Other changes include minor modifications to src/app.rs, src/event.rs, src/game.rs, src/lib.rs, src/model/config.rs, and src/widget/button.rs to accommodate the new gesture support feature.