Remove deprecated XP System since PMMP has already implemented it

[CortexPE]

pmmp/PocketMine-MP@418d099 🎉

I might do this tomorrow... busy rn. kcya

[TDMidkwhatisxd]

] [Server thread/CRITICAL]: Could not tick level "world": Call to undefined method pocketmine\Player::getTotalXp()
[21:34:03] [Server thread/CRITICAL]: Error: "Call to undefined method pocketmine\Player::getTotalXp()" (EXCEPTION) in "TeaSpoon_dev-103.phar/src/CortexPE/utils/Xp" at line 59
[21:34:03] [Server thread/DEBUG]: #0 TeaSpoon_dev-103.phar/src/CortexPE/entity/XPOrb(99): CortexPE\utils\Xp::addXp(pocketmine\Player object, integer 2)
[21:34:03] [Server thread/DEBUG]: #1 src/pocketmine/entity/Entity(1328): CortexPE\entity\XPOrb->entityBaseTick(integer 1)
[21:34:03] [Server thread/DEBUG]: #2 src/pocketmine/level/Level(759): pocketmine\entity\Entity->onUpdate(integer 18466)
[21:34:03] [Server thread/DEBUG]: #3 src/pocketmine/Server(2379): pocketmine\level\Level->doTick(integer 18466)
[21:34:03] [Server thread/DEBUG]: #4 src/pocketmine/Server(2536): pocketmine\Server->checkTickUpdates(integer 18466, double 1515188043.1473)
[21:34:03] [Server thread/DEBUG]: #5 src/pocketmine/Server(2276): pocketmine\Server->tick()
[21:34:03] [Server thread/DEBUG]: #6 src/pocketmine/Server(2151): pocketmine\Server->tickProcessor()
[21:34:03] [Server thread/DEBUG]: #7 src/pocketmine/Server(1739): pocketmine\Server->start()
[21:34:03] [Server thread/DEBUG]: #8 src/pocketmine/PocketMine(554): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string /root/12/tst/, string /root/12/tst/plugins/)
[21:34:03] [Server thread/DEBUG]: #9 /root/12/tst/PocketMine-MP.phar(1): require(string phar:///root/12/tst/PocketMine-MP.phar/src/pocketmine/PocketMine.php) 34:03] [Server thread/CRITICAL]: Could not tick level "world": Call to undefined method pocketmine\Player::getTotalXp()
[21:34:03] [Server thread/CRITICAL]: Error: "Call to undefined method pocketmine\Player::getTotalXp()" (EXCEPTION) in "TeaSpoon_dev-103.phar/src/CortexPE/utils/Xp" at line 59
[21:34:03] [Server thread/DEBUG]: #0 TeaSpoon_dev-103.phar/src/CortexPE/entity/XPOrb(99): CortexPE\utils\Xp::addXp(pocketmine\Player object, integer 2)
[21:34:03] [Server thread/DEBUG]: #1 src/pocketmine/entity/Entity(1328): CortexPE\entity\XPOrb->entityBaseTick(integer 1)
[21:34:03] [Server thread/DEBUG]: #2 src/pocketmine/level/Level(759): pocketmine\entity\Entity->onUpdate(integer 18466)
[21:34:03] [Server thread/DEBUG]: #3 src/pocketmine/Server(2379): pocketmine\level\Level->doTick(integer 18466)
[21:34:03] [Server thread/DEBUG]: #4 src/pocketmine/Server(2536): pocketmine\Server->checkTickUpdates(integer 18466, double 1515188043.1473)
[21:34:03] [Server thread/DEBUG]: #5 src/pocketmine/Server(2276): pocketmine\Server->tick()
[21:34:03] [Server thread/DEBUG]: #6 src/pocketmine/Server(2151): pocketmine\Server->tickProcessor()
[21:34:03] [Server thread/DEBUG]: #7 src/pocketmine/Server(1739): pocketmine\Server->start()
[21:34:03] [Server thread/DEBUG]: #8 src/pocketmine/PocketMine(554): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string /root/12/tst/, string /root/12/tst/plugins/)

Just wanted to post xdddddd