Currently, all of the functionality lies at most in functions. Now it is
easier for dividing responsibility between the Font and Urxvt classes,
and easier to understand what is going on.
Using some of the nerd fonts[1] urxvt can display glyphs, which are
available there, but still, there is a several other glyphs, which are
defined in different font files, than Deja Vu, which I'm using as a main
scalable font.
Moreover, I really like to use Fixed Misc[2] from Xorg, since it's crisp
and readable.
In this commit, urxvt will have a list of fonts passed to, instead of
only one, to have greater number of glyphs to display.
[1] https://www.nerdfonts.com/
[2] https://gitlab.freedesktop.org/xorg/font/font-misc-misc
