tests predicates according to the boolean interpretation of their return value, not expecting specifically true or false

Respecting Genuine assert_equal false Edition

This avoids the unnecessary "yo dawg, I heard you like include, so I put a module that includes your module when it is included" approach when building extensions.

Revert "tests predicates according to the boolean interpretation of their return value, not expecting specifically true or false"

Reason: there were some genuine tests for false when
reading values, going to revise those ones.

This reverts commit a539a5e3.

tests predicates according to the boolean interpretation of their return value, not expecting specifically true or false

This is done since the -h option to dbconsole hides the conventional
-h for help and forces users to use --help to see the usage options for
dbconsole.

Bump Arel

This reverts commit 3178cc9a.

updating API docstring so that user can infer default value

fix rails plugin new CamelCasedName bug

refs #3684

Meaningful errors for unexpected partial arguments. Fixes #3573

If we're deleting all records in an association, don't add a IN(..)
clause to the query.

Fixes #3672.

Use `show index from`. We could fix `pk_and_sequence_for` method's performance problem (GH #3678)

adapters.

These tests fail on the v3.1.2 tag.

Closes #3690.

Warning removed for shadowing variable

This reverts commit 9d725e3df502a07222f35576108eb2df2bd88259.