Update comments
Left align the legend to its column container

Note that "horizontalAlignment" is a new parameter in MapFish print
2.0-SNAPSHOT, and did not exist in 1.2.1-GEORCHESTRA version used
until georchestra/georchestra@2253e1b7.

Unfortunately, the parameter default has been set to "center", which
breaks compatibility with previous behavior. We then need to
explicitely set the parameter in confg.yaml.
Limit legend texts width, and wrap them.

Note that this only affects legend texts managed by MapFish print, and
not legend icons labels, that are included inside the images returned
after the WMS GetLegendGraphic query.

Note also that these legend icons labels are always appended to the icon,
since mapfishapp pass the "LEGEND_OPTIONS=forceLables:on" GeoServer vendor
parameter. There is no mean to know exactly the resulting size of the
generated image, and no GeoServer parameter to restrict the label size,
therefore the two MapFish parameters that control the legend icons size
are let undefined (iconMaxWidth and iconMaxHeight).

This means that, whereas the legend texts managed by MapFish are wrapped
when they hit the legend max width, the image containing the icons and
the icons labels might overflow to the right of the page, and some part of
the label would be hidden, in case these labels are too long.
Scale down legend icons to match map icons size.

In the case of a WMS map, MapFish sends the dpi parameter to the
map server (be it GeoServer or MapServer) to get a bitmap generated
wit that dpi resolution (ie. a double size image if resolution is
~180dpi). MapFish then manages the dpi to include the map tiles with
the adequate size into the PDF.

In the case of a WMS legend, MapFish does not manage the dpi parameter,
and directly includes the image form an URL as provided by the client
(mapfishapp, using GeoExt). As well, GeoExt does not manage dpi vendor
parameter of GeoServer.
See http://docs.geoserver.org/latest/en/user/services/wms/get_legend_graphic/legendgraphic.html#controlling-legend-appearance-with-legend-options
for details on the GeoServer dpi vendor parameter in GetLegendGraphic.

Unless/until both GeoExt and Mapfish manage the dpi resolution for
legend icons generation, these are generated using the default
GeoServer dpi resolution, which is 90.71 (25.4/0.28), and not 91 as stated
in its documentation.

The ~91 dpi resolution corresponds to the bitmap space, whereas PDF
lengths are expressed in paper space, with a 72 dpi resolution. This
transformation from bitmap space to paper space is managed by MapFish
only for the map, as stated above.

We then need to do the same transformation manually, in order the
map icons and the legend icons to get the same size.

Note: whereas this commit fix the size mismatch, the resolution
will remain different when map dpi is greater to ~91dpi. In case
the resolution is 300dpi, for example, the map resolution would be
good for printing, but the legend resolution would remain ugly.
Merge branch '13.09'