Corrected main file.

Changed the indent width as explained in this document:
https://docs.google.com/document/d/1YXk9kitfJWyamkwLn2o0_k-hK_fSeQILusQfY-czW7o/edit#heading=h.92h1bu6nnyd1
(Document no one read anyway).

Translated comments in english.

Added doxygen comments at the beginning of file and before
main function.

Included <stdlib.h> because of atexit().