Feat(Ruler): Allow grid unit steps less than 0. Also fixes incorrect counting of cells in grid mode.

[rexy712]

I realized that PA doesn't allow decimal numbers as a grid unit size while trying to make a regional map for use in an army combat scenario. I wanted to make hexes each 0.1 miles, and the UI appeared to let me, but it was silently being rejected.

I thought that it wouldn't hurt anything to allow such grid measurements, even if not very applicable to most situations. I feel like with the hex grid now working much smoother, it allows for more regional or overworld style map usage, at least in games like Pathfinder.

While I was working on this, I needed to make the 'Grid Mode' of the ruler tool function and noticed a couple bugs in the distance shown on screen. I fixed those issues while I was in working on that file since they were rather straightforward. Those being

• Measuring from a starting cell and remaining in that cell showed a distance of -1 cells
• Measurements in Grid Size Units were always 1 increment greater than they should have been.
• Using multiple rulers would give incorrect distances

[Kruptein]

Ah you should also mention the QoL change to the spell tool in the changelog!

Ideally that was a separate PR, but I can ignore that for once ;)

[rexy712]

Ah you should also mention the QoL change to the spell tool in the changelog!

Ideally that was a separate PR, but I can ignore that for once ;)

I kinda thought of it as a part of this work since the spell tool scales to fit the grid unit size, which is why I included it here.

It does seem like a separate issue that could have been done as a separate pull request. I'll try to better separate next time!