[solver] Fix Solver with variable-length symbols

apps/solver/equation_store.h

@@ -20,7 +20,7 @@ public:
     TooManyVariables = -2,
     NonLinearSystem = -3,
     RequireApproximateSolution = -4,
-    VariableNameTooLong
+    VariableNameTooLong = -5
   };
   /* EquationStore */
   EquationStore();

apps/solver/solutions_controller.cpp

@@ -160,7 +160,6 @@ void SolutionsController::willDisplayCellAtLocation(HighlightCell * cell, int i,
           break;
         default:
           int length = strlcpy(bufferSymbol, m_equationStore->variableAtIndex(j), Equation::k_maxVariableSize);
-          bufferSymbol[0] = m_equationStore->variableAtIndex(0);
           bufferSymbol[length++] = j+'0';
           bufferSymbol[2] = 0;
           break;