raise default "max_connections" value to 100

Documentation says the limit is 5, but it was really 10 (at least
since 2004).  But since MPD wants to promote using many small clients
idling around, and these clients consume only very few resources, it
seems reasonable to raise this limit's default value.

src/Main.cxx

@@ -460,7 +460,7 @@ MainOrThrow(int argc, char *argv[])
 #endif
 
 	const unsigned max_clients =
-		raw_config.GetPositive(ConfigOption::MAX_CONN, 10);
+		raw_config.GetPositive(ConfigOption::MAX_CONN, 100);
 	instance->client_list = new ClientList(max_clients);
 
 	initialize_decoder_and_player(raw_config, config.replay_gain);