Implement foreign namespace protocol

I beleive this to be the last critical piece for Rakudo work.

nt/namespace.t

@@ -0,0 +1,20 @@
+# vim: ft=perl6
+
+plan(2);
+
+pir::load_bytecode("perl5.pir");
+my $p5 := pir::compreg__ps("perl5");
+
+$p5.make_interp('
+    package Foo::Bar;
+    sub Method {
+        my ($self, $x, $y) = @_;
+        return $x + $y;
+    }
+')();
+
+my $ns := $p5.get_namespace('Foo::Bar');
+
+ok(pir::defined($ns), "can get namespaces for packages");
+
+ok($ns.Method(1,3,7) == 4, "can call package methods");

perl5.pir

@@ -189,6 +189,17 @@ Implements the PDD-31 library loading interface.
     .return (name_str)
 .end
 
+.sub 'get_namespace' :method
+    .param pmc name
+
+    self.'!force'()
+
+    $P0 = getattribute self, '$!interp'
+    $P0 = $P0.'get_namespace'(name)
+
+    .return($P0)
+.end
+
 .sub 'get_exports' :method
     .param pmc module_name
     .param pmc imports :slurpy