Error: `nullptr` was not declared in this scope. Arduino IDE
I installed Arduino IDE in two different ways (only god knows why). The first one was via using of manager apt-get and other was manually via downloading, unzipping and installation through the install.sh file.
It seems that on Ubuntu 14.04 the

sudo apt-get install arduino


command provides an installation of an old version of Arduino IDE.
So eventually I was launching Arduino IDE by arduino command in my terminal (actually I was using d-menu in i3). No surprise it ran the old one installed by apt-get. I just removed that version by

sudo apt-get remove arduino


And now I am using executable arduino inside unzipped folder. Actually, I am not using Arduino IDE explicitly at all. I am using a Makefile from here.