opensimplex2

[lmas]

• [x] Wait for KdotJPG to finish his FastNoiseLite work
• [ ] Research and summarize improvements
• [x] Upgrade source
• [ ] Add numpy optimizations per #4
• [x] Investigate maintaining multiple versions and pypi releases (numpy optimized or not, opensimplex2S or 2F) Hmm nope, see #4
• [ ] Normalize function names in all versions (including v3, which breaks compatibility?!)
• [ ] Document output values from multiple sources (python, go, C#)?
• [x] Inspect output image quality
• [ ] Fix the tests (gonna need a whole new suite of tests..)
• [ ] Update README (breaking name changes, v0.3 deprecrated, new imgs, examples, clarify it's opensimplex2 but lib is v0.4)
• [ ] Release v0.4-pre (with warnings about breaking changes?)

[lmas]

I'll put this work on v2 on hold for now.