Minor refactoring of writeOuterClass()
Write correct InnerClasses attribute to class files

InnerClasses should contain entries for every inner and every outer class,
according to the JVMS

 #KT-3390 Fixed
KT-2874 Exception in front-end when extending Java class

 #KT-2874 Fixed
Make TaskPrioritizer not abstract, added private constructor.
Removed redundant assert.
Converted anonymous to inners.
Moved loadJava "general" tests to subdirectory.
Updated generated tests according to moving general load Java tests to subdirectory.
Subclassed LoadJavaCustom from same class as AbstractLoadJavaTest (for moving test method).
Subclassed from AbstractLoadJavaTest and moved all common code there.
Reduced visibility of methods.
Replace pair parameter with pair of parameters.
Reused method.
Minor. Added assert message.
Moved compiledJava cases to generated test.
Removed redundant code.
Minor. Simplified code.
Added namespace classes to Java static member scope.
Don't complete packages for Java static classes in package directive.
Fixed useless hidden import & useless simple import diagnostics when Java class is resolved as both class and namespace.