Provide multiple pride maps in PrideGiftList

This would allow players to receive one of 20 maps from the PrideGiftList as an hourly gift. The map would be chosen at random.

The maps are the ones that I and RebelCommander7 have built with assistance from MilesHis and Abamacus. This includes 6 solid-colour maps for the colours of the 6-colour flag.

I have also adjusted the weight of filled maps in the list accordingly. It is proportional to the number of maps in the pool, so the list can easily be adjusted while making any map individual map as likely as a normal item.

Updated item probabilities for the modified Pride gift list:Pride.csv