#51 #52 AF Corse WEC + Le Mans 2021 1.1.1

All four liveries now (correctly) have transparent headlights instead of yellow tinted (thank you @kkamiloos !)

This update contains the liveries that were raced at the 2021 Le Mans 24h, where #51 picked up its second class win in three years, while #52 hit trouble, including a spectacular front right tyre explosion out of Mulsanne corner.

Also includes small updates to the WEC skins, which carry over to the LM version as well (#52 now has its splitter trim correctly painted gold, not red; the black details above the diffuser have a more correct shape).

Please let me know if I missed something. #54 coming soon as well!

Two small fixes:

- Fixed an annoying error on the #51 windshield where the Italian flag was not transparent and also quite badly pixelated (very noticeable when driving);

- Switched the two livery.png files to the correct (WEC) versions. The current Le Mans livery.png will come in handy for a Le Mans version of the skins later this year.