SVGHMI: detachable and discardable elements sets, Reworked geometric intersection, toward more accurate page content detection.

Moved page's widget/element dependency crawling functions so that it is possible to compute a global detachable and discardable elements sets.
Reworked geometric intersection detection logic to distinguish ovelapping and inclusion.
Goal is to include englobing and overlapping graphical elements, but not groups (would then include everything around...). Intermediate commit, to be continued.

#!/bin/sh

INKSCAPE=inkscape

for fname in `ls *.svg`; do
    for i in `cat $fname |grep -o -e '%%[^%]*%%'|sed 's/%//g'` 
    do
        if [ $i.png -nt $fname ]; then
 	    echo "Skip $i"
        else
	    rm  -f $i.png
	    echo "$INKSCAPE" $fname -z -e $i.png -i $i
	    "$INKSCAPE" $fname -z -e $i.png -i $i
        fi
    done
done

cp ico024.png brz.png
convert -compress none ico*.png brz.ico
rm -f ico*.png


convert -compress none poeico*.png poe.ico
rm -f poeico*.png