First draft of relax command extension

[matentzn]

Fixes #1060, #1183

• [X] docs/ have been added/updated
• [X] tests have been added/updated
• [X] mvn verify says all tests pass
• [X] mvn site says all JavaDocs correct
• [X] CHANGELOG.md has been updated

These PR extends the relax command by adding three new options:

• --exclude-named-classes: if true, A EquivalentTo B between named classes are excluded from relax
• --include-subclass-of: if true, A Subclass A and R some B is relaxed the same way as A EquivalentTo A and R some B, see @cmungall request in #1183
• --enforce-obo-format: If true, only simple existentials and named subsumptions are asserted during the process

I like all the functionality, but the --enforce-obo-format is really clunky. I would be happy if someone made a better suggestion; I also dont like --exclude-nested.

The only "breaking" change in this PR is that the CLI gets --exclude-named-classes by default as true. Previously, before this option existed, A=B was relaxed to A sub B and B sub A. No one I personally now has ever said that this is a good idea, so we changed the default, as discussed in #1060.