actived solveSimpleEquations for simulation

[vruge]

With this commit move some work of ExpressionSolve from SimCode to Backend
benifite:

• don't lose preprocessing/modefication of Expression from ExpressionSolve if ExpressionSolve is failed
• fixes for #3091

open issues with order:

• call this model earlier break #3091, because some module discarded comps
• don't can be at the beginnig in postOptModules
• before removeSimpleEquations --> running in the issues with HeatingSystem which described in https://trac.openmodelica.org/OpenModelica/ticket/3742#comment:21

[OpenModelica-Hudson]

Wrong hash OMCompiler 75fe4c7 48b3784

[OpenModelica-Hudson]

The tests run correctly according to OpenModelica_TEST_PULL_REQUEST 2016-03-20_23-54-20.