Rename namespace class to {package.name}Package

Conflicts:

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

compiler/testData/writeSignature/ListOfCharSequence.kt

@@ -1,7 +1,7 @@
 
 fun foo(p: List<CharSequence>) = 1
 
-// method: namespace::foo
+// method: _DefaultPackage::foo
 // jvm signature:     (Ljava/util/List;)I
 // generic signature: (Ljava/util/List<+Ljava/lang/CharSequence;>;)I
 // kotlin signature:  (Ljet/List<Ljava/lang/CharSequence;>;)I // TODO: skip Kotlin signature