Add 256x256 and 64x64 Beremiz icons


remove svg:midPointStop tags from icons.svg, because Inkscape
complained about unsupported tag. It seems that these tags were made
by Adobe Illustrator and aren't supported by any other app.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<ProcessVariables xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>