Polylines using map space line widths can disappear completely using AGG renderer

[chrisclaydon]

Polylines should never be allowed to disappear entirely - the minimum line weight should be set to 1.0. This will give consistent behavior between the AGG and GD renderers. When zoomed in, the lines will be rendered with a width corresponding to a real world size. When zooming out, the lines will become steadily narrower until they reach the minimum line width. They will then maintain that width with subsequent zoom-out operations so that they never disappear entirely.

[chrisclaydon]

Fixed by submissions:

​http://trac.osgeo.org/mapguide/changeset/2798

​http://trac.osgeo.org/mapguide/changeset/2799