OEF should warn developer of duplicate names before generating a new node

[cdietric]

Before generating a new node, it would be good to list any other nodes that have identically named device managers and/or devices (this can be done by parsing the dcd files of the existing nodes). The developer should be given the option to continue or cancel. In a multi-node system, device managers and devices all need to have distinct names. Look for tags like the following:

<deviceconfiguration name="DeviceManager?" id="DCE:26555f88-e859-11db-97b9-00123f573a7f"> and

<usagename>GPP1</usagename>

[cdietric]

Note that the DeviceManager? name is a default value for all new nodes. The developer could be given the option to change it before generating the node, or less ideally, the developer could be told what edit to make in the dcd file.

[stedwar2]

Need to implement #187 first.