Batch editing for treegrid

This is batch editing example for a treegrid, it's similar to batch editing for grid example with few differences.

addNodes and deleteNodes methods of Tree() are used to add and remove nodes in Treegrid instead of grid addRow and deleteRow methods.

Add new nodes

While adding new nodes, Tree().addNodes() method expect id of the new nodes, so we generate random id with prefix "pq_tmp" which is replaced by the actual id returned by the server.

grid.Tree().addNodes([{ EmployeeID: "pq_tmp_" + Math.random(), FirstName: "new item" }])

Nodes having id with prefix "pq_tmp" are treated as new nodes by tracking module and are not confused with existing nodes.

On server side:

When id of a new node present in addList is generated, its value is filled as parentId for children nodes present in addList.