#13 Fixed issue with reverse axis - some WFS services needs different
order of coordinates in bbox parameter. Therefore, a new parameter was
added: "reverseAxisBbox". If true only coordinates in the bbox request
will be swapped.
#13 Fix for removeLayer. Was not working because each feature in a WFS
(vector) layer constitutes an own layer. Therefore, the "layeradd"-event
is triggered for each and every feature in the vector layer. This
means only the last feature in the layer will be stored in the _layers
object (which is used for keeping track of added layers in the smap
framework).