Update to Rock Generator & UI!

Hello! After a long silence, I've updated the prop generator!

This has been the result of work I've been putting in on a related project, and the changes largely concern two areas - the UI, which has been overhauled somewhat and made much simpler for me under the hood; and the Rock Generator, which should now be able to make more varied and potentially more interesting rocks.

Tooltips have been updated to briefly explain what each parameter in the rock generator do, though if you want some clarification I'll happily expand on it. The source code has not yet been updated, since the code is now more deeply embedded in another project I'm not comfortable sharing quite yet - that may come at a later date.

There are a few known issues:

• Sometimes, corner geometry generates with small gaps. Still tracking down the math that's causing this to happen.
• Sometimes, clicking on tabs that extend beyond the side panel doesn't properly point the UI at the right data.

I've completely updated the rock template file structure, and made minor changes to the others, so old templates will no longer work! This is unfortunate, but this is primarily a tool I'm using to assist me in other projects; I have very little time to work on it in a dedicated way, and I'm mostly sharing it as a curiosity. Still - it should work well enough for the time being!