Improve `brew doctor` autocrlf check.

Closes #15711.
Cleanup old bottle syntax.
Don't use underscores in (new) bottle filenames.

Closes #14270
Add pour_bottle? method to Formula.

Allows a formula to selectively disable bottle pouring.
e.g. the default Boost bottle does not work with a brewed Python.

Fixes #17142
Improve the explanation of the verbose flags.

Closes #17181.