fixed size of XBoard icon to 48x48 the icon gets installed in the 48x48 directory, but was >200 pixel wide. This gave a warning during rpm creation.
better contrast for XBoard icon on a dark background
added logo files for xboard logos are installed in the hicolor theme [1] using $datadir as the basedir. Added both png and svg logo. [1] http://standards.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html