* now we have 2 class : 1 for the marker and 1 for the group. When a marker is "alone", the class of the marker is used, if it is grouped with others markers, the class of the group is used.
* markers with the same class are grouped. If 2 markers do not have the same class they are not grouped.
* an icon can be set by the user for a single marker or a class
* the theme have 3 different markers/groups : radio, radio2 and empty (only the numbers of markers and the icon are displayed)
* we can specify to display a group's class only for a zoom >= to a value. It means a marker of this group is not displayed for a zoom < to this value.
* off course we have new bugs too :)
SVN revision: 44610
Jonathan Atton