Choose columns to be returned

[akaer]

Columns that should be returned must be configurable to speed things up.
Support the EntityLoadtype directly:

• Default: Loads read-only entities according to the supplied query.
  Loaded columns include the primary key, display columns according to the display pattern, some special columns, and the columns defined in the select clause of the query. The entries are sorted by the defined display or the optional orderBy clause of the query. This load type is the default and be omitted.
• Slim: Works mostly like Default but does not load display columns and does not build an orderBy clause per default. This type is useful when loading data not intended for display and can save much time by using database indexes.
• BulkReadOnly: Loads read-only entities with all columns filled. The columns defined in the query are overridden.
• ForeignDisplays: Loads display values for foreign keys contained in the display pattern. This allows showing displays instead of UIDs for foreign keys.
• ForeignDisplaysForAllColumns: Like ForeignDisplays, but loads displays for all foreign keys contained in the select clauses of the query, not only columns referenced in the display pattern.