Always create aliases for non-namespaced classes

Talked about this with @kiesel following a weird situation he'd encountered in one of his projects:

Our current "optional namespace" support doesn't work for the following situations:

Situation 1
--
```php
try {
  raise('webservices.rest.RestException', 'Test');
} catch (\webservices\rest\RestException $expected) { 
  echo "OK";
}
```

**Expected**
```sh
OK
```

**Actual** 
```sh
Uncaught exception: Exception lang.reflect.TargetInvocationException (xp▒runtime▒Dump::main)
  at lang.reflect.Method::invoke(NULL, array[1]) [line 95 of class.php]
Caused by Exception webservices.rest.RestException (test)
[...]
```

Situation 2
--
The same occurs for type hints

```sh
$ xp -w '$f= function(\lang\Object $o) { return 1; }; return $f(new Object());'
1

$ xp -w '$f= function(\lang\Object $o) { return 1; }; return $f(new Object());'
Uncaught exception: Exception lang.reflect.TargetInvocationException (xp▒runtime▒Dump::main)
  at lang.reflect.Method::invoke(NULL, array[1]) [line 95 of class.php]
Caused by Exception lang.IllegalArgumentException (Argument 1 passed to xp▒runtime▒Dump::{closure}() must be an instance of lang\Object, instance of Object given
[...]
```

Reason
--
The `ZEND_CATCH` opcode doesn't trigger autoloading like e.g. `new`, `instanceof` or static references to not yet loaded classes do. This is because `catch` will never be able to catch classes that haven't previously been loaded, because they must have been instantiated for use with `throw` before. The same reasoning was applied to type hints: For the value we're receiving to be able to be an instance of the given type hint, it must've been instantiated before. And to be usable, the class must have been loaded before.

Because we only created aliases when the **autoloader** was invoked (and not when classes where explicitely loaded via `eval`, `include` or `require`, which is what our class loading infrastructure does), the alias was not in place when the class was explicitely loaded.

Solution
--
This pull request solves this problem by **always creating alias namespace names** for all non-namespaced classes.