has_many must use the inverse fk when query

[fixes #3242]
Update changelog
Merge pull request #3253 from mongoid/inverse_fk

has_many must use the inverse fk when query
make sure to not add duplicate keys on many_to_many
refactoring accessors .get_relation_for_set
always return self on contextual .each
Fix find_or_create_by with custom persistence.

[ fix #3243 ]
Revert "Fix find_or_create_by with custom persistence."

This reverts commit e2e88d45bdc99e6d9808c6b91bdb04673caf56eb.
db:test:prepare now creates all indexes.

[ close #3141 ]
Allow multiple belongs_to sets in a row with ids.

[ fix #3137 ]
Update changelog
Adding spec for #3123
Fix combo of Uniqueness Validator + Aliased + Localized
Fix combo of Length Validator + Aliased + Localized
Fix combo of Presence Validator + Aliased + Localized
Update changelog
Override account _id field
Adding positive spec for #3261
Don't convert single elements to arrays:

Applies to $addToSet, $push, $pull, $pullAll.

[ fix #3262 ]
Merge branch 'master' into threading_issue