Rename namespace class to {package.name}Package

Conflicts:

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

compiler/testData/writeSignature/declarationSiteVariance/InInInPosition.kt

@@ -2,7 +2,7 @@ class In<in T>
 
 fun f(p: In<String>) {}
 
-// method: namespace::f
+// method: _DefaultPackage::f
 // jvm signature:     (LIn;)V
 // generic signature: (LIn<-Ljava/lang/String;>;)V
 // kotlin signature:  (LIn<Ljava/lang/String;>;)V