Version 2.6.1
- modified find_free_edges to continue when an atom is found to
  be completely inside another atom

Version 2.6.0
- Dual density support:
  It is now possible to compute a molecular surface with 2 densities of 
  vertices.
  The command line accepts a new keyword "hdensity" for specifying the vertex 
  density to be used in the high density region.
  The high density region is specified by a flag for each atom.
  This modification creates a backwards incompatibility with .xyzrn file 
  format as the optional high density flag is located before the name field 
  in the input file.

- Code was added to force subdivision of edges in cycles made of only 2 edges.

- Added the ability to restart the calculation if the reduced surface fails 
  to build because of numerical instability. 

Version 2.5.7

- Fixed the type field of vertices.  Type 3 for vertices inside reentrant 
  faces, 2 for vertices in toroidal faces and SES edges and vertices,
  and 1 for points inside contact faces.

2.5.6

