Oneof ambiguity

Issue: Messages that hold one of multiple sub messages (the "oneof" keyword) have varying names for the sub message: Sometimes it is "type", some other times it is "message" and sometimes it is a unique meaningful name, e.g. "AbstractAlertDescriptorOneOf".

Should be consistent.

Proposal: Use meaningful names everywhere.

Messages to change:

• DiscoveryMessage [deprecated?]
• SearchFilter
• ProxyNotifyHelloAndByeRequest
• ProxySubscribeHelloAndByeResponse
• Filter
• EpisodicReport
• EpisodicReportStream
• PeriodicReport
• PeriodicReportStream
• OperationInvokedReportStream

Some of these are generated by the proto converter, some are defined manually.