CustomRelations
----------------------
This sample shows how to create relations in code, specifying the list of child rows dynamically at run time.

Using custom relations, you can create arbitrary complex master-detail
hierarchies in data bound controls, even if you can't express it in
terms of a regular relation between table fields. 

To create a custom relation, open Edit Relations dialog of a C1ExpressConnection
component, specify the parent and child tables of the relation and
check the GetRowsEvent check box. Then write code in the C1ExpressConnection.GetChildRows
event implementing your custom algorithm for obtaining child rows for this relation.

In this sample, custom relation "Orders - Products" is used to implement a
many-to-many relationship between Orders and Products using Order Details
as an intermediary (join) table.

Relations "Orders - Order Details" and "Order Details - Products"
are hidden from data binding by unchecking the MasterDetail check box.
So, the DataGrid control does not show these two relations to the user, they
are only available programmatically. The only relation DataGrid control
shows is "Orders - Products".
