Renaming a macro if there is a function with the same name

If the script contains a function with the same name as any macro, then the macro will be renamed, which will lead to incorrect execution.

Example:
```AutoIt
func Tab()
    return @tab
```
will be translated to
```AutoIt
func _myscript_Tab()
    return @_myscript_Tab
```
while the following is expected:
```AutoIt
func _myscript_Tab()
    return @tab
```