Add support for user defined attributes / manual overload resolution

Adds support for the following attributes on class methods:
* NoScript - Prevents the method from being registered.
* ScriptRename(newname) - Changes the method's registration name to newname (so if you had `A::foo @ScriptRename(bar)` it'd be registered as `A::bar`).
* ScriptAffix(affix, isSuffix) - Changes the method's registration name to include a prefix or suffix.

__Utility__
* Allows binding properties and other overloaded functions correctly, if the user specifies alternate function names.
* Allows the user to hide internal APIs (useful in games for example, where it might be beneficial to have access to renderer stats in Lua but without including the rest of the renderer's functions) with reduced boilerplate.

__Issues__
This still doesn't solve the base problem of registering overloaded functions and ideally pushMethod  and pushOverloadedMethod would be written with a more generic pushMethod as their base.

__Example__

```D
class A
{
	int _x = 10;

	int x() @property
	{
		return _x;
	}

	void x(int nx) @property @ScriptAffix("Set")
	{
		_x = nx;
	}

	void sayhello() @ScriptRename("hello")
	{
		writeln("hello");
	}

	void internalfunc() @NoScript
	{
		// ...
	}
}

A a = new A();
lua["a"] = a;

// In lua code
print(a:x()) // 10
a:Setx(2)
print(a:x()) // 2
// a:sayhello()  -- error, doesn't exist
a:hello() // "hello"
// a:internalfunc() -- error, doesn't exist
```
This needs to be an alias, not a manifest constant, otherwise it will fail in certain cases.