Changes to quick explode

- fix python error when the object had an empty material slot
- initialize start frame from the current frame
- set frame range to 300000 max (which is blenders own maximum)
- mesh order was arbitrary, instead use selected -> active, removed invert option.

also fix for missing include in bpy_extras.view3d_utils

release/scripts/modules/bpy_extras/view3d_utils.py

@@ -114,6 +114,8 @@ def location_3d_to_region_2d(region, rv3d, coord):
     :return: 2d location
     :rtype: :class:`Vector`
     """
+    from mathutils import Vector
+
     prj = Vector((coord[0], coord[1], coord[2], 1.0)) * rv3d.perspective_matrix
     if prj.w > 0.0:
         width_half = region.width / 2.0