feat: draft freehand highlighter

[DerpDays]

This is will add a freehand highlighter as the default (with shift to align it), and then have a selection highlight (like there currently is) accessible by pressing ctrl whilst on the highlighter, since this was suggested at some point (though since currently the highlighter tool is the selection it might make more sense to make the freehand one accessible through ctrl instead), currently this is just draft and needs quite a bit of cleanup.

EDIT: kept the block/selection highlighter as the default, with the freehand/line highlighter being the alternative highlighter, this is configurable via the CLI or config.

[00-kat]

though since currently the highlighter tool is the selection it might make more sense to make the freehand one accessible through ctrl instead

I think (not a dev, just a random user) that it should probably be an option you can set in the config file.

[DerpDays]

yeah that's probably best, i'll get to working on this in a few days so it can finally not be a draft

[gabm]

I agree.. I didn't have a look at the PR, @DerpDays let me know if I can help

[DerpDays]

Sorry for the large delay & also the large commit (this should have been broken down into quite a few more commits).

This should mostly ready, here's an overview of the new things:

• Adds a new highlighter, which is a freehand line/pen highlight, by default it is the secondary highlighter meaning it is accessible with CTRL, by pressing SHIFT while highlighting it aligns it from the previous point that was not aligned. To make it easier to make perfect turns, you can release SHIFT to add an extra point (and do it again to remove the point if you want) when you haven't moved the cursor.
• Removed the border around the block highlighter since its not necessary and inconsistent with other tools apart from the blur tool.
• Added a SHIFT option for the block highlight to make a square highlight.
• Configuration/command line options to change the primary highlighter to the line highlighter.
• Add a new event for tools: key_release which as implied is when a key is released (in contrast to the previous event of when pressed)

Let me know if there's anything that needs changing or can be done better.

[00-kat]

If you start holding shift mid-way should it draw a straight line from the beginning or from the spot you started holding shift from (it does latter rn)?

[DerpDays]

The spot you started holding shift from, thought it'd give more options for how people want to draw it, since you can just hold shift when starting the highlight to achieve the other effect

[gabm]

I just tested it, it looks great!

[gabm]

Thank you for this great contribution :partying_face: