[Dune] FS#223 Bug in solve and invert of FieldMatrix fixed

[Markus Blatt]

Dear Dune Users,

may I point your attention to flyspray bug #223
http://hal.iwr.uni-heidelberg.de/flyspray/?do=details&id=223 

There was a serious bug in the privoting used both for the solve and
the invert method of FieldMatrix. This means that whenever the
absolute diagonal value of a row of FieldMatrix A became less than
1E-14*|A| during the lu decomposition the result was wrong.
Here | | denotes the infinity norm of the matrix.

This is fixed in revision 4823.

I would recommend updating and running calculations again as this
might have incluenced them.

Cheers,

Markus