Add missing thread names, improve existing thread names

This extends on the work of PR #2323.

Since thread names are limited to 15 characters, we reduced the length of the name (removing starting C, get rid of spaces, remove trailing Thread, ...) where it made sense.

```
xbmc02:~ # pstree -p 715
xbmc.bin(715)-+-{EPGUpdater}(798)
              |-{EventServer}(790)
              |-{PeripheralBus}(778)
              |-{PeripheralBus}(779)
              |-{PVRAddon}(800)
              |-{PVRAddon}(932)
              |-{PVRGUIInfo}(933)
              |-{PVRManager}(799)
              |-{SoftAE}(777)
              |-{TCPServer}(791)
              |-{XBPython}(783)
              |-{XBPython}(784)
              |-{XBPython}(786)
              |-{XBPython}(787)
              |-{XBPython}(955)
              |-{XBPython}(972)
              `-{xbmc.bin}(792)
```

I would like to see more specific names for XBPython, PeripheralBus and PVRAddon. And also get rid of the remaining xbmc.bin thread name.