[vdr] Update cached names

[Wolfgang Goeller <wgoeller@heraklit.ch>]

Hello

It's a good thing that vdr caches the recordings and does not need
to search the files. But sometimes this method has disadvantages.
Say I make a recording of several documentations - as you get it
from ARTE. When I edit this mulit-recordings, I do split them and
each record get's its own name. But now there is no way to remove
the recordings from the vdr menu.
Just to be precise:
I record "Arte_Themenabend" then I split it to
%Sonntags_nie
%Melina_Mercouri
In the list of the recordings from vdr I have only
%Arte_Themenabend - which in fact doesn't exist.
The only way to update the recording-list is to restart vdr.
There should be a button to make vdr reread it's cache.
Alternatvie would be if vdr would update it's cache when
there are no other activities

Regards
Wolfgang