Extension of barycenters to (Fused) GW, several bug fixes around LR Sinkhorn, parallel (segment) code for Sinkhorn, inits for ICNNs

What's Changed

• Refactoring problems.py by @marcocuturi in #86
• Feature/gw losses by @michalk8 in #88
• Fix/lr linear apply by @michalk8 in #91
• Addition of ICNN Initialization Schemes by @bunnech in #90
• Fix/point cloud apply cost fn by @michalk8 in #93
• Feature/lr gw apply output by @michalk8 in #96
• Remove legacy online option by @michalk8 in #97
• Feature/fast tests by @michalk8 in #101
• Fix/axis norm by @michalk8 in #103
• Generic LR cost decomposition by @michalk8 in #99
• Remove pytest-memray from test req, use only in CI by @michalk8 in #107
• demo and fixes for barycenters of GMMs by @ersisimou in #89
• Add (F)GW barycenters by @michalk8 in #87
• Feature/notebook tests by @michalk8 in #108
• [ci skip] Fix duplicate bibtex entry and a typo by @michalk8 in #109
• GW different cost ranks by @michalk8 in #113
• segment_sinkhorn by @marcocuturi in #114
• Create CODE_OF_CONDUCT.md by @marcocuturi in #118
• Fix/padded scaling by @michalk8 in #116

Full Changelog: 0.2.7...0.2.8