Rename namespace class to {package.name}Package

Conflicts:

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

compiler/testData/writeSignature/declarationSiteVariance/PropertySetterIn.kt

@@ -3,7 +3,7 @@ class X
 
 var p: M<X> = throw Exception()
 
-// method: namespace::setP
+// method: _DefaultPackage::setP
 // jvm signature:     (LM;)V
 // generic signature: (LM<-LX;>;)V
 // kotlin signature:  null