Fixed link issue, improved Makefile

Fixnuty problem s linkovanim s najnovsim gcc na ubuntu 12.04. Link flagy maju ist vzdy na koniec. Dalej CC = compiler C a CXX = compiler C++ nikdy sa nedefinuju explicitne, pochadzaju z prostredia aby si uzivatel mohol pouzit vlastny compiler ako ja napr. clang.

Build s clangom (toto som nefixol nakolko som sa nesprtal v kode):

    clang++ -Wall -c OptionParser.cpp
    clang++ -Wall -c PlayField.cpp
    clang++ -Wall -c main.cpp -pthread
    clang++  OptionParser.o PlayField.o main.o -pthread -o redbot
    clang `pkg-config --cflags gtk+-2.0` -o gui gui.c `pkg-config --libs gtk+-2.0`
    gui.c:63:1: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^
    gui.c:363:1: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^
    2 warnings generated.