[Kst] Still some problems with plugins and locks...

[Brisset, Nicolas]

Since George's change yesterday, I can now use some plugins (e.g. shift)
and it seems to work OK. However, others still have problems:

QMutex::unlock: unlock from different thread than locker
                was locked by 0, unlock attempt from 4
QMutex::unlock: unlock from different thread than locker
                was locked by 0, unlock attempt from 4
QMutex::unlock: unlock from different thread than locker
                was locked by 0, unlock attempt from 4
QMutex::unlock: unlock from different thread than locker
                was locked by 0, unlock attempt from 4
kst: Curve 127*V0^3+243...-C-kstfit_polynomial_unweighted-C said UPDATE

This happens with the small test file in
.../kst/src/plugins/fits_nonlinear/general_levenberg_marquardt/test_fit.
kst which creates a simple vector and a polynomial equation to test
fitting algorithms. When I load test_fit.kst and try to do a polynomial
fit, kst freezes with the above message.

It wasn't clear whether yesterday's fix was meant to solve all problems,
or just some cases so I thought I'd mention it...

Nicolas