fixed a compiler crash because with noopt, strings weren't put on the heap

compiler/src/prog8/CompilerMain.kt

@@ -104,10 +104,12 @@ private fun compileMain(args: Array<String>) {
             }
             //println(" time4: $time4")
 
+            val allScopedSymbolDefinitions = moduleAst.checkIdentifiers(heap)       // useful for checking symbol usage later?
+//            moduleAst.simplifyExpressions(namespace, heap)
+//            moduleAst.optimizeStatements(namespace, heap)
             if(optimize) {
                 // optimize the parse tree
                 println("Optimizing...")
-                val allScopedSymbolDefinitions = moduleAst.checkIdentifiers(heap)       // useful for checking symbol usage later?
                 while (true) {
                     // keep optimizing expressions and statements until no more steps remain
                     val optsDone1 = moduleAst.simplifyExpressions(namespace, heap)

compiler/src/prog8/ast/AstIdentifiersChecker.kt

@@ -33,6 +33,7 @@ fun Module.checkIdentifiers(heap: HeapValues): MutableMap<String, IStatement> {
             }
             else -> TODO("replace literalvalue by identifierref: $variable  (in $parent)")
         }
+        variable.second.linkParents(scope as Node)
     }
 
     printErrors(checker.result(), name)

examples/test.p8

@@ -5,9 +5,6 @@
 
     ; @todo see problem in looplabelproblem.p8
 
-    ; @todo when using -noopt, the error "can only push address of string that is a variable on the heap" appears when using strings
-
-
 
     sub start() {