0.7.5 Release : Hot-patch 1 — After the Collapse Steam update #127182

Here's a small hot-patch for 0.7.5. Nothing major it's fixing several small issues with spider/scorpion nests, which when combined would cause the critter population to grow way beyond what's intended over time. It's also adding ways for modders to add their own ores to mountains without interfering with the base game files. Also, and this need a bit of an explanation, a weird bug was reported recently: mountains/caves would always uncover ores when mined. It was due to a technical problem with the way I accessed the random number generator from multiple threads. It would cause the RNG to stop working as intended in extremely random and rare cases. This is now fixed, but there was a small price to pay, map generation will take a bit longer now, not by much, but I guess it might be noticeable on larger maps / older computers. As usual with hot-patches, it's compatible with previous 0.7.x ...