Pysr

What's Changed

- Faster evaluation for constant sub-expressions ([SymbolicRegression.jl129](https://github.com/MilesCranmer/SymbolicRegression.jl/pull/129))
- Will now check variable names for spaces and other non-alphanumeric characters, aside from underscores. Before this would only raise an issue after a search, when trying to pickle the saved data.


**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.11.2...v0.11.3

(Fix for conda-forge build)

**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.11.1...v0.11.2

What's Changed
* Update backend https://github.com/MilesCranmer/PySR/pull/191
* Includes high-precision constants when `precision=64`
* Enables datasets with zero variance (to allow fitting a constant)
* Changes, e.g., `abs(x)^y` to `x^y`, with expressions avoided altogether for invalid input. This is because the former would sometimes give weird functional forms by exploiting the cusp at `x=0`. Thanks to johanbluecreek.

**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.10.4...v0.11.0

What's Changed
* Fix install for Julia <=1.6 by MilesCranmer mkitti in https://github.com/MilesCranmer/PySR/pull/188
* PyJulia will now launch directly into the shared `pysr-{version}` environment, rather than activating it later.

**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.10.3...v0.10.4

What's Changed
* Displays a warning message when PyTorch is imported *before* PyJulia starts. See https://github.com/pytorch/pytorch/issues/78829. The only current solution is to start Julia beforehand.
* New [docs](https://astroautomata.com/PySR/)! Using Material-Mkdocs:
<img width="1445" alt="Screen Shot 2022-09-06 at 6 06 49 PM" src="https://user-images.githubusercontent.com/7593028/188748940-e6e0262b-3567-4819-9169-efecc174c59c.png">

What's Changed
* Set JULIA_PROJECT, use Pkg.add once by mkitti in https://github.com/MilesCranmer/PySR/pull/186


**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.10.1...v0.10.2