Shop items unlocking

• you now must reach a certain XP level to unlock a shop item
• once the item unlocked, you need to pass a challenge to be able to equip it

New Shop Layout

• split the avatar customization and shop items into two pages
• better layout of all the shop items in the shop
• display of the total gain in attributes

Various bugs fixed and small improvements. Don't forget to report any bug or ideas to our Discord. NEVER STOP RIDING