PyPSA/linopy: v0.1

What's Changed Composition design review by @FabianHofmann in https://github.com/PyPSA/linopy/pull/63 fix minor typos in doc strings by @lumbric in https://github.com/PyPSA/linopy/pull/70 Refactor LinearExpression and Constraint using composition by @coroa in https://github.com/PyPSA/linopy/pull/55 Support writing problem to MPS file by @FabianHofmann in https://github.com/PyPSA/linopy/pull/71 Modularize tests by @FabianHofmann in https://github.com/PyPSA/linopy/pull/72 fully support integer variables by @FabianHofmann in https://github.com/PyPSA/linopy/pull/73 Add constants module for static parameter by @FabianHofmann in https://github.com/PyPSA/linopy/pull/74 A set of constant status and termination conditions by @FabianHofmann in https://github.com/PyPSA/linopy/pull/76 [pre-commit.ci] pre-commit autoupdate by @pre-commit-ci in https://github.com/PyPSA/linopy/pull/75 Automatic summation of repeated variables by @FabianHofmann in https://github.com/PyPSA/linopy/pull/77 Support diff operation for variables and expressions by @FabianHofmann in https://github.com/PyPSA/linopy/pull/79 Filter out very small coefficients by @FabianHofmann in https://github.com/PyPSA/linopy/pull/80 Improve representation of infeasible constraints by @FabianHofmann in https://github.com/PyPSA/linopy/pull/81 [pre-commit.ci] pre-commit autoupdate by @pre-commit-ci in https://github.com/PyPSA/linopy/pull/82 Improve representation by @FabianHofmann in https://github.com/PyPSA/linopy/pull/84 supress disturbing output when cbc/glpk are no available_solvers by @jankaeh in https://github.com/PyPSA/linopy/pull/87 Solver options printout by @FabianHofmann in https://github.com/PyPSA/linopy/pull/86 [pre-commit.ci] pre-commit autoupdate by @pre-commit-ci in https://github.com/PyPSA/linopy/pull/83 Improve repr follow up by @FabianHofmann in https://github.com/PyPSA/linopy/pull/88 New Contributors @jankaeh made their first contribution in https://github.com/PyPSA/linopy/pull/87 Full Changelog: https://github.com/PyPSA/linopy/compare/v0.0.15...v0.