[Nepomuk] The last issues to solve in the Virtuoso backend

[Sebastian Trüg]

First the good news: The Virtuoso backend works!
After some commits I made today it is more stable and reliable as last week.
However, there are still some issues to resolve:

1. large literals.
With Strigi indexing files we get the plain text representation of many files. 
These can be very large. Inserting them into Virtuoso takes a long long time. 
Especially if we run it in lite mode with little memory usage.
Currently the backend simply ignores large literals. This, of course is no 
solution. I am currently in contact with OpenLink about that problem. But any 
other input is very welcome.

2. query encoding
Apparently there are still some character that are not properly encoded in 
queries. I was told that % chars sometimes confuse Virtuoso. 
I ask you to please test as many queries as possible and report back problems 
(or ever better: provide patches to resolve the issues. ;)

3. Shutting down Virtuoso.
If Virtuoso is still working when we try to shut it down it simply ignores the 
command. Even killing it does not always work (at least not with 
QProcess::terminate()). Input welcome.

Cheers,
Sebastian