For each annotation, add a feature to allow the user to add a category

Allow zoom-in and zoom-out.

• Allow labelling in zoomed mode, but scale + translate the points from the zoomed-domain to the normal domain

When going between images, draw the "focussed" line the same thickness it was when it was drawn (right now, it changes it to what the thickness bar was previously set at)

• This may be related to setting the sliding line-thickness bar to the correct value when writing images

Display the default mode in the bottom bar by correctly clicking the button by default

Duh

In cursor mode, clicking should not lay a point that becomes visible when you switch to another mode.