change the sequence of the process to keep them the same as before.
correct one compiling error. refer to the right class, although it is not actually used.
now the class need template arguments. We do not need to tell which activity model it is, because the default one is the unity acitivity coefficients.
adding the function overwriteLastTimeStepValue
register the equilibrium reaction system class.
move all content to chemEqReactSys.h.
temperary solution.