Compiler: scoping rules can be violated

```
if(something())
{
    integer foo = 42
}
else
{
    foo = 666
}


This nonsense compiles and executes, albeit with undefined behavior. Fix 
scoping rules to be enforced properly.
```

Original issue reported on code.google.com by `don.ap...@gmail.com` on 5 Sep 2014 at 5:33
