Rename namespace class to {package.name}Package

Conflicts:

	compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java

compiler/testData/writeSignature/declarationSiteVariance/InOfInInOutPosition.kt

@@ -3,7 +3,7 @@ class X
 
 fun f(): In<In<X>> = throw Exception()
 
-// method: namespace::f
+// method: _DefaultPackage::f
 // jvm signature:     ()LIn;
 // generic signature: ()LIn<LIn<-LX;>;>;
 // kotlin signature:  ()LIn<LIn<LX;>;>;