Remove deprecations [4.0]

[sbosley]

This PR kicks off our 4.0 development branch by removing all the deprecated methods, fields, and behavior from the 3.x branch. Specifically:

• SquidDatabase.onDowngrade now returns false by default
• Removes all the various generated methods and fields for the ID field in table models. All models in 4.0 should be using either rowid or an explicitly declared primary key field. Also removes restrictions on user properties named ID -- any user-declared property, even a non-primary key one, can now be named ID. Only ROWID is reserved.
• Removes deprecated SQL compilation methods that used VersionCode instead of CompileContext
• Other misc deprecated methods/fields that have either been removed, renamed, or refactored into better alternatives

[sbosley]

Definitely yes, I was planning to write a bunch of test cases that cover the migration from 3.x to 4.0 (and I also think we should release a 4.0 beta for people to experiment with and report any issues). I'll fix that extra 'a' in a future PR.