- Replaced std::cout and std::cerr with logging to file, so now all the messages should be saved
- Removed friend operator << functions from cInventory classes

Signed-off-by: Jan Nemecek <Nemecek.Jan@seznam.cz>
- Fixed RenderText error spamming when empty string was passed to function. There is still issue with '\n', as it seems this char is not rendered as text properly. Need to fix it.

Signed-off-by: Jan Nemecek <Nemecek.Jan@seznam.cz>