Change station cargo history storage format

Use uint16 to avoid truncation issues
Don't reserve memory for unused cargoes
Store history as ring buffer
Update history graph immediately on storage date
Show total waiting cargo

src/station.cpp

@@ -78,7 +78,8 @@ Station::Station(TileIndex tile) :
 	indtype(IT_INVALID),
 	time_since_load(255),
 	time_since_unload(255),
-	station_cargo_history{}
+	station_cargo_history_cargoes(0),
+	station_cargo_history_offset(0)
 {
 	/* this->random_bits is set in Station::AddFacility() */
 }