Ruler for Freehand Draw about notekit

[blackhole89]

This is a great addition, thanks! I'm currently away at a conference and so can't look at the implementation in detail, but two suggestions:

• Rather than deciding the orientation based on the first motion after the painting begins (which I do think is too noisy and just generally frustrating to use), I think it would be better to determine it based on the inclination between the starting point and the current mouse position, so a wrongly aligned line could be "corrected" by moving the pointer elsewhere. (This does imply that the alignment of past segments of the line currently being drawn would change after the fact and would have to be rotated.)

• I would prefer for there to be a pointer-only way of accessing drawing-related functionality (in case someone wants to draw with their keyboard folded away, for instance). Maybe something like a button3-triggered popover menu (in spirit of this) or a separate mode (maybe accessible by right-clicking the drawing tool in the toolbar) would work?

Unrelatedly, you are the second person (after @freemin7) whose screenshots show the colour picker in the toolbar to have a sequence of black (x6), red and black again, rather than the default colours (as seen in the screenshot in README.md). How come? Was it this way when you first installed notekit? Can you edit the colours by right-clicking them?

[freemin7]

@blackhole89 I think that happened over time. I can edit color slots by right clicking but did not change them to be all black. Not sure what happens there.

Also this feature looks really good.