(Gene-trees) Long wedges are shortened and hatched

(copy of the earlier pull-request)

Hi again,

When the branches are too long, they are divided by 10, 100, etc, but not when they are collapsed. It causes pictures like: http://www.ensembl.org/Homo_sapiens/Gene/Compara_Tree?g=ENSG00000155363;r=1:113215763-113243368

The fix divides the length of the wedges by 10, 100, etc, following the same rule, and draws the wedges with hatchings:
http://enssand-01.internal.sanger.ac.uk:9073/Homo_sapiens/Gene/Compara_Tree?g=ENSG00000155363;r=1:113215763-113243368

Another example:
http://www.ensembl.org/Homo_sapiens/Gene/Compara_Tree?db=core;g=ENSG00000073910;r=13:32605437-32870794
http://enssand-01.internal.sanger.ac.uk:9073/Homo_sapiens/Gene/Compara_Tree?db=core;g=ENSG00000073910;r=13:32605437-32870794

I didn't manage to add the symbols to the legend. I've found where to add entries, but I couldn't make triangles with the same pattern

Matthieu