Changed the implementation of LisMatrix::getMaxDiagCoeff().

- Removed the update code for calculation of _max_diag_coeff from
  + LisMatrix::setValue()
  + LisMatrix::addValue().
- Removed the _max_diag_coeff attribute.
- Implemented the functionality in LisMatrix::getMaxDiagCoeff().
Added parameter for penalty to applyKnownSolution(), some formatting.
Move up using boost ptree directive.
Qualify const LisMatrix class attributes.
Comment LisMatrix class attributes 'is' and 'ie'.
Reset _is_assembled flag on modifications.
Correct lis vector row access in getMaxDiagCoeff().
Qualify const LisVector class attributes.
LisMatrix.cpp: Fixed indentation.
Using attribute _is_assembled to ensure correct usage of LIS.