Money&Coins

Added coin drop mechanic :

• If the player dies, a portion of his money stored in the Coin Menu will drop on the floor.
• FIxed gamerule coinDropRate, that set the proportion of coins which will be drop upon player's death (the proportion is calculated in tenth of pourcent, 0 is disabled and 1000 makes all your money drop, default is 50).
• Added new gamerule doDroppedCoinDespawn. If false, dropped coin upon death won't despawn (default is true)

Fixes :

• Fixed bug that put your money in negative values when you withdraw all your gold coins.
• Your money will be recalculated when you close the Coin Menu.