Fix generation of FMI 1.0 import

Bad code was generated previously, causing OM to try to get string
parameter values by creating an algebraic loop. This causes string
parameters to be fixed so the start-value is used instead.

Belonging to [master]:
  - #2101
  - OpenModelica/OpenModelica-testsuite#816

Author: sjoelund

Compiler/Template/CodegenFMU.tpl

@@ -2740,7 +2740,8 @@ case "1.0" then
   match variabilityCausality
   case "parameter" then
     if boolAnd(hasStartValue,isFixed) then " = \""+startValue+"\""
-    else if boolAnd(hasStartValue,boolNot(isFixed)) then "(start=\""+startValue+"\",fixed=false)"
+    /* If we set fixed=false, we generate bad code; let make OM handle the bad values */
+    else if boolAnd(hasStartValue,boolNot(isFixed)) then "(start=\""+startValue+"\")"
     else if boolAnd(boolNot(hasStartValue),isFixed) then "(fixed=true)"
     else if boolAnd(boolNot(hasStartValue),boolNot(isFixed)) then "(fixed=false)"
   case "" then