Compile leaficon_small.xpm directly into canvas.cpp and revert changes that added a separate icon directory.

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user: Michael Guravage <michael.guravage@cwi.nl>
branch 'default'
added src/leaficon_small.xpm
changed src/ChangeLog
changed src/VirtualLeaf-install-windows.nsi
changed src/canvas.cpp
removed icons/leaficon.png
removed icons/leaficon_small.png