[Box] variable switch at boundary
It seems that there is a bug in the variable switch for box at the boundary.
In the initPriVarSwitch_ method, the states of Dirichlet nodes are corrected.
This method is called in newtonBegin, which however is called after the initialization
of uLastIter.
Therefore, when calling the newtonUpdate method, the corrected states of uCurrentIter
are overwritten.
We could fix this by either calling initPriVarSwitch_ before uLastIter is initialized
or by setting this vector after newtonBeginStep.
So we could simply change
if (numSteps_ > 0)
uLastIter = uCurrentIter;
to
if (numSteps_ >= 0)
uLastIter = uCurrentIter;