Multiple changes.

- Remove the runtime dependency on rake-compiler.
 - Use #rb_str_new instead of #rb_str_new2, the hash character array
   isn't null terminated.
 - Add various safeguards for object instantiations.
 - Remove the 'threaded' options for messages, folding them into
   'archived'.  If archiving is enabled, so is threading.
 - Return nil for lookups from the list object instead of raising
   exceptions.
 - Open subject indexes with the proper encodings (thanks Michael
   Granger!)
 - Allow touching and unlinking files to operate on multiple paths
   at once, within a single safety() wrap.

ext/ezmlm/hash/hash.c

@@ -148,12 +148,12 @@ address( VALUE klass, VALUE email ) {
 
 	Check_Type( email, T_STRING );
 
-	email = rb_str_plus( rb_str_new2("<"), email);
+	email = rb_str_plus( rb_str_new2("<"), email );
 	input = StringValueCStr( email );
 
 	makehash( input, strlen(input), hash );
 
-	return rb_str_new2( hash );
+	return rb_str_new( hash, 20 );
 }