Mining update bugs

[ISaidNo]

A couple of things:

- The new sprites are an improvement. Bohrum ore veins are still very hard to spot at a glance though.
- Char ore has a hardness rating of -1 instead of 0.
- Will ore extractors have a future? Worthless without a teleporter upgrade (should be standard), but they were useful sometimes. Failed to find any dense asteroids so far.
- Digbots don't have different sprites for the on/off states.
- Pathfinding appears broken. They mine adjacent tiles just fine, yet don't move around on their own. Different settings and tiles (space vs. catwalk/asteroid) don't seem to make a difference.
- Emagged digbots should probably attack people with the pickaxe instead of doing nothing.

1) I changed some of the ore colors the other day so you can spot them a bit easier. Keep the feedback coming.
2) That's intended. Char is a weak crumbly material that weakens the structure of the rock, so it's easier to dig out than usual.
3) Dense asteroids are currently gone, so extractors are currently useless. I am working on something to do for them though!
4/5/6) Digbots are kind of useless to be honest and I might just do away with them.

This was just me being a dumbass with the spawn asteroid debug proc. It's not a regular occurrence!

Did you change the algorithm for ore distribution yesterday? I couldn't find any morliz or cobryl in four different asteroid fields.

I did add two new ores but that shouldn't stop those from showing up. Keep at it over the course of a few days and let me know.