Chaning using the new interpolation for viscosity
Rewriting the d_mu_d_p for deadGas.
Updating the calculation of mu and dmudp for PvtDead.
A little more comment about B and b.
Changing the PvtLiveOil  to use 1/BV for viscosity.

Pssing the simple 2D test.
Finshing changing Pvt_liveGas

Remains to be verfied.
Using resize to allocate memory for 1/BMu.
Fixing the blackoilfluid test.
Merge remote-tracking branch 'upstream/master' into PVT_viscosity_try
Fixing test_wetgas in test_blackoilfluid.
Changing the naming in PvtDead.

To be consistent with the naming int PvtLive.
Deleting some commented lines.
Changing the location of * in long formula.
Changing nColumns to nRows.
Changing the tolerance for blackoilfluid tests.

Using the original strict relative tolerance for other properties than viscosity.
Merge pull request #657 from GitPaean/PVT_viscosity_try

Obtaining viscosity by doing a linear interpolation of the inverse of B*mu instead of mu directly.