Tracking issue for 0.3.0 release

[j-ti]

Prepare

• [x] Go through branches together: keep/ create PR/ delete

Do

• [x] Testing (Check all components also for the "Adapt new oemof structure #113 "):
  • [x] all tests written - Stefan, Ciara, Julian (25.2)
  • [x] review tests #236 - Julian (25.3.)
  • [x] run tests with new oemof structure #113
• [x] Issues:
  • [x] #234 - @b-r-u ?
  • [x] Activate Travis again - @b-r-u ?
  • [x] #233 - delete interactive plotting function - Ciara (25.2.)
  • [x] #173 store save important parameters locally (GOGS) and delete function - Ciara (25.2)
  • [x] also delete rtd for 'interactive plotting function' and 'save important parameters ' - Ciara (25.2)
• [x] PRs:
  • [x] #235 - Julian (11.3.)
  • [x] #181 - Julian (11.3.)
  • [x] steam methane reformer - Ciara prepares PR #243 - julian/laura (25.2.)
  • [x] unify create_oemof_model behaviour -> rename: add_to_oemof_model - julian (25.3.) #251
  • [x] julian makes PR: delete DC AC and AC DC generate generic electric converter - julian (11.3.) #248
  • [x] include oemof.thermal - julian (11.3.) part of #113
  • [x] merge #113

Finalize

• [x] Release 0.3.0 by changing setup.py, doc/conf.py and adding a tag to commit
• [x] Check all requirements
• [x] Fix flake8 warnings
• [x] Update Changelog (also how to change from 0.2.0 to 0.3.0)
• [x] merge master
• [x] :robot: :tada: