Fixes #2955: Changed the signature of ActiveQuery constructors and `ActiveRecord::createQuery()` to simplify customizing ActiveQuery classes

allow extending only one class to add scopes, fixes #2146

TODO:

- [ ] adjust guide docs
- [ ] adjust README files of extensions
- [ ] finish work and fix test breaks

fixes #1993

meet the AR interface requirements.

now supports mapped primary key when _id is part of source with an
alias.

- allows to have dynamic definition of attributes depended on the
  instance
- there was no real need for it to be static. Places that used it static
  have been refactored.

fixes #1318

Appended newlines to every PHP document that did not have a newline as the last character in the file.

Added support for scopes defined in AR classes.

finished AR documentation.