boundaryCondition initial work.
make general.
make symmetric and solve with CG
bug fix for comparison with q
Merge branch 'develop' of https://github.com/simpeg/simpeg into boundaryConditions
Merge branch 'develop' of https://github.com/simpeg/simpeg into boundaryConditions
Merge branch 'develop' of https://github.com/simpeg/simpeg into boundaryConditions
Testing BC for cell-centered system

- inhomogenous neumann BC
- Mixed BC

were tested

Fixing bug in the function "projNeumannIn"
Testing boundary conditoins

- I am not sure what happend... but this is what I did for last push
Merge branch 'boundaryConditions' of https://github.com/simpeg/simpeg into boundaryConditions
Updates to plotSlice to work on irregular grid
updates to plotSlice
minor bug fix.
Merge branch 'develop' of https://github.com/simpeg/simpeg into boundaryConditions
Lowered tolerance on utility tests
Added check on modelPair in Problem.
Minor updates.
Docs reorganization.
Added nonLinearModel Object
updates to problem and data.