Create an RRDD plugin functor, and use it to create the local plugin module.

Signed-off-by: John Else <john.else@citrix.com>
Add skeleton Interdomain module.
Add the functorised functions to the RRDD interface.

Signed-off-by: John Else <john.else@citrix.com>
Hook the old API calls up to the functorised versions.

Signed-off-by: John Else <john.else@citrix.com>
Remove unneeded code.

Signed-off-by: John Else <john.else@citrix.com>
Implement registration of rrdd plugins by xenopsd.

Signed-off-by: John Else <john.else@citrix.com>
Add an argument to open_handle.

This is needed so that the grant reference gets passed to the
interdomain version of open_handle.

Signed-off-by: John Else <john.else@citrix.com>
Implement Interdomain.open_handle

Signed-off-by: John Else <john.else@citrix.com>
Implement Interdomain.read_data

Signed-off-by: John Else <john.else@citrix.com>
Compile data sources from both Local and Interdomain plugins.

Signed-off-by: John Else <john.else@citrix.com>