Removed non-default constructor from FlameSolver
Updated notnan to work with Eigen::Map types
Switched from [] to () for indexing some Eigen arrays

Preparation for converting several types to Map types, which do not support
indexing with square brackets.
Started to separate split integrator from FlameSolver

The new class SplitSolver holds the actual variables used in the split
integration. The arrays in the FlameSolver class are "views" into the global
arrays using Eigen::Map.
Make use of the new aggregate state arrays where possible
ConvectionSolverSplit shares state with FlameSolver

This removes the need to copy the state vector into the split term integrator
and back out after every convection step.
Renamed mathUtils::near to mathUtils::almostEqual

Fixes a conflict with the macro named 'near' defined in windef.h when
compiling on Windows.