added transform routine for expr -> RPN

codeGenExperimental/src/prog8/codegen/experimental/ExperiCodeGen.kt

@@ -16,6 +16,10 @@ class ExperiCodeGen: ICodeGeneratorBackend {
         options: CompilationOptions,
         errors: IErrorReporter
     ): IAssemblyProgram? {
+
+        // If we want RPN expressions instead, use this:
+        // program.transformBinExprToRPN()
+
         // you could write a code generator directly on the PtProgram AST,
         // but you can also use the Intermediate Representation to build a codegen on:
         val irCodeGen = IRCodeGen(program, symbolTable, options, errors)