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.

Beremiz's user manual
=====================

Contents:

.. toctree::
   :maxdepth: 2

   install
   start
   edit
   build
   connectors
   debug