merge @JetProperty and @JetMethod

because:
* have common parts
* reduce class size

Also add helper JetMethodAnnotationWriter class

And also do not generate @Jet* annotations for closures

compiler/frontend/src/org/jetbrains/jet/lang/descriptors/NamedFunctionDescriptor.java

@@ -3,6 +3,8 @@ package org.jetbrains.jet.lang.descriptors;
 import org.jetbrains.annotations.NotNull;
 
 /**
+ * ... and also a closure
+ *
  * @author Stepan Koltsov
  */
 public interface NamedFunctionDescriptor extends FunctionDescriptor {