Revert "Rewrite kolory.cpp" and "Change file extensions"

This reverts commits 3190df5 and dfeadd4. You can find them in cpp
branch.
Rewrite czas.c.

- use more spaces for better readability
- remove useless comments
- declare iteration variables inside loops
- get rid of conio.h; instead of using getch, add posibility to exit
  the program with 0
Convert source files to Unix format.