Unify call args rewrite

It's still not perfect. There are two problems:
On the Java target, the unit tests cannot compile with the following error:
```
/usr/lib/haxe/std/java/_std/haxe/ds/WeakMap.hx:409: characters 11-18 : java.lang.ref.WeakReference.T should be haxe.ds.WeakMap.K
```
It seems that this comes from `WeakReference::get()` being seen as returning `T`, not `K`. This seems to come from an inversion of parameters somewhere. See the private class Entry.

On the C# target, it fails at runtime because it can't find `_IndexOf`. `_IndexOf` is a static function which later had its name changed to `IndexOf` with the `@:native` metadata. It seems that the classfield at `FStatic` is a copy, since the cf_name change didn't propagate to that instance.

We'll talk better about those tomorrow! See ya