Added: Example for a custom field configuration
Tested: Query custom field
Implemented: Direct query to custom field definition
Implemented: Allow setting custom fields for field and fulltext search queries

The patch introduces a setCustomField method on field and fulttext
criteria, so that the user of the API can specify which field to query
instead of the default field. An example for such a custom field can be
found in the schema.xml
Throw not implemented exception for unknown criteria in legacy search
Moved check out of loop
Added: @throws documentation
Documented interface
cs
Update doc