Update pl-PL.lang

Progress: 51,5% [404/784]

26th June: All achievements translated
30th June: Buffs and NPC responses translated; fixed a typo
11th July: Combo messages, creative tabs, death messages, temple names, skills, some mobs done. Sorry for being slow, having problems with electricity lately :(
Merge pull request #3 from kamild1996/patch-2

Update pl-PL.lang