dvdplayer: keep copy of internal state of dvdplayeraudio

This avoids external threads messing with internal objects like
audio renderers.
[python/json] Add DPMS (de)activate announcements to python's monitor class and the JSON definition
[appmessenger] Send announcements upon DPMS state change
Merge pull request #4766 from herrnst/dpms-message

[python/json/appmessenger] Announce DPMS state change to XBMCMonitor and JSON
[python] bump python API after 647269ae62fdae2fd4279781f315a8495428af9c
jsonrpc: bump API version after 647269ae62fdae2fd4279781f315a8495428af9c