Example & documentation updates

[speth]

Changes proposed in this pull request

• Start populating the FAQ
• Add more entries to the glossary
• Fix some small display issues in the docs
• Add ReactorNet drawing (introduced in #1624) to a couple of examples
• Revise several examples to have nicer looking output in Sphinx Gallery
• Reorganize Python examples into fewer categories
• Add more links between the tutorials and the examples (resolves Cantera/cantera-website#103)
• Add warnings about the deficiencies and failure modes of the Mixture class and the multiphase equilibrium solvers

If applicable, fill in the issue number this pull request is fixing

Closes Cantera/cantera-website#103

Checklist

• [x] The pull request includes a clear description of this code change
• [x] Commit messages have short titles and reference relevant issues
• [x] Build passes (scons build & scons test) and unit tests address code coverage
• [x] Style & formatting of contributed code follows contributing guidelines
• [x] The pull request is ready for review

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 72.79%. Comparing base (ded4513) to head (40abe2c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1724 +/- ## ========================================== - Coverage 72.80% 72.79% -0.01% ========================================== Files 381 381 Lines 54011 54011 Branches 9207 9207 ========================================== - Hits 39321 39319 -2 - Misses 11706 11707 +1 - Partials 2984 2985 +1 ```

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[bryanwweber]

@speth will you fix the examples in this PR? I'm not sure if the failures are related to this branch. If not, I'll approve :smile: