More intuitive navigation controls.

[RustyRaptor]

I find it rather frustrating that there is no way to drag the canvas around. A simple feature to be able to middle click and drag to move around the canvas would make all the difference.

[RustyRaptor]

It seems this works fine in the web version of the app with the middle click button. I am guessing this doesn't carry over into electron apps for some reason.

[NickGeek]

@tinkergod raised this issue too with #237. I posted this message here:

Hi, agreed. On Windows it seems like the electron app doesn't get this behaviour but the functionally identical web app (https://web.getmicropad.com) does. I personally use a mouse with left/right scroll on it or laptops with trackpads that can scroll.

I'm not sure what the main approach here would be but https://github.com/MicroPad/MicroPad-Core/blob/master/app/src/app/components/note-viewer/NoteViewerComponent.tsx would be a good place to look.