[pvr.tvh] link events with recordings and vice versa

See https://github.com/xbmc/xbmc/pull/3900 for what it's supposed to do. I haven't tested this yet.
Okay, so I guess what's really needed is something like this (ignoring the correct strcpy() syntax):

```
const std::string recordingId = ss.str();
strcpy(epg.strRecordingId, recordingId.c_str())
```