Clean up protocol code generators

xC-gen-proto-js.awk

@@ -51,6 +51,8 @@ function define_uint(size,    shortname) {
 }
 
 function codegen_begin() {
+	print "// Code generated from " FILENAME ". DO NOT EDIT."
+	print ""
 	print "export class Reader extends DataView {"
 	print "\tconstructor() {"
 	print "\t\tsuper(...arguments)"