Add support for native WMS rotation to the print module

[ahocevar]

See http://www.mapfish.org/pipermail/dev/2010-February/000552.html.

The attached patch adds this feature. To make use of it, a client should add an angle param to the customParams of a layer, with -rotation as value, rotation being the rotation configured in the print page. The advantage over using the print module's rotation is that labels of the rotated map will still be horizontal.

Please review.

[ahocevar]

An example of printed output with this new option. Note the horizontal labels.

[elemoine]

Andreas, why do we need support from the print server module for that? The client should just not set "rotation" if it sets the "angle" custom WMS param, no?

[ahocevar]

Think about the case where the map about to be printed consists of 2 layers. One is from a WFS that supports the angle param, the other from one that does not. How would you do that then?

[elemoine]

(In [3426]) Add support for native WMS rotation to the print module, p=ahocevar, r=me (closes #558)