Python3-compatible

This is a long-overdue release of linsolve, which has long been Python3 compatible, but here is the release that publishes it.

What's Changed

• Consts speedup by @AaronParsons in #20
• changed weights to 1/sigma^2, fixed chi^2, and clarified the documentation by @jsdillon in #21
• Made all the necessary changes for python2/3 compatibility. Mostly t… by @AaronParsons in #22
• Logcal bugfix by @AaronParsons in #23
• Solver mode by @AaronParsons in #24
• fix installation-order issues by @steven-murray in #25
• lineqn bug fix when data.shape=(1,1) by @nkern in #27
• Remove python 2 tests and support by @jsdillon in #29
• CPU speedup by @AaronParsons in #28
• Migrate from Travis to GitHub Actions by @jsdillon in #34
• Update for numpy 1.20 by @jsdillon in #35
• Tidied up Numpy1.20 upgrade to infer_dtype by @AaronParsons in #37

New Contributors

• @steven-murray made their first contribution in #25
• @nkern made their first contribution in #27

Full Changelog: v0.0.1...v1.0.0