- refactored elasticsearch AR to make type and index available in
  instantiate(), issue #1313

fixes #2281

fixes #1993

Fixes #1579: throw exception when the given AR relation name does not match in a case sensitive manner.
Renamed `ActiveRecord::getPopulatedRelations()` to `getRelatedRecords()`

Moved file and path related methods from StringHelper to FileHelper, renamed StringHelper byte methods not to be misused as string methods

- 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

Model::attributes() has been made static

this allows us to implement other activerecord implementations based on
NoSQL dbms

[ci skip]