Merge pull request #7 from Aloalo/master

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Merge pull request #8 from Aloalo/master

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Merge pull request #9 from Aloalo/master

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Merge pull request #10 from Aloalo/master

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Merge pull request #11 from Aloalo/master

even more
GUI

UIManager klasa
Component klasa
Container klasa
Button klasa
LayoutManager klasa
VerticalLayoutManager klasa
Jednostavni gui u testeru
Refactor input klasa
Refactor input observer
Event klase
Funkcije input observera primaju event objekte
Merge pull request #7 from toi333/master

GUI