Add support for the linopy io_api option

[koen-vg]

Sorry for the barrage of issues and pull requests. I do think this is a nice and simple improvement.

Changes proposed in this Pull Request

Big fan of the io_api = "direct" option that linopy provides for HiGHS and Gurobi; it improves performance and actually solves some problems I've had with .lp files eating up too much disk space on funky cloud setups.

Checklist

• I tested my contribution locally and it seems to work fine.
• Code and workflow changes are sufficiently documented.
• Changed dependencies are added to envs/environment.yaml.
• Changes in configuration options are added in all of config.default.yaml.
• Changes in configuration options are also documented in doc/configtables/*.csv.
• A release note doc/release_notes.rst is added.

[koen-vg]

By the way this isn't worth a new issue but @fneum you seem to have accidentally added your personal config to the last commit to master.

[koen-vg]

Actually this seems to cause a problem with the snakemake workflow always re-running the solve_network rule; please don't merge until I fix it.

[koen-vg]

Nevermind, the re-running thing doesn't seem to be a problem with the present PR but with d145758! Feel free to merge this if desired.

[koen-vg]

Actually this seems to cause a problem with the snakemake workflow always re-running the solve_network rule; please don't merge until I fix it.

The re-running issue is now fixed in #893

[fneum]

Nice addition!

Out of curiosity: Performance increases were in terms of memory or time?

[koen-vg]

Out of curiosity: Performance increases were in terms of memory or time?

Definitely in terms of time; using the direct API keeps things in memory meaning that writing the .lp and reading it again is avoided; the time savings surely depend quite a bit on the file system. Of course it shouldn't matter for the time or memory taken by the actual solver: it "doesn't care" if it was fed a problem via python API or .lp file. Total memory use I haven't checked but don't think it changes much overall.