Option to start numbering the vertices from zero instead of one.
Program to construct the corona of graphs
Code to calculate edge connectivity of a graph in multicode format
Added option for creating horizontal outer faces

A horizontal outer face is an outer face in which the bottom edge is horizontal
Changed letter to toggle horizontal outer faces

The letter h was already used for the help message
Files can now be split to one graph per file
Allow the extension to be changed
Corrected minor bug that caused larger graphs to be output incorrectly
dual_pl can now also include the original graph in its output

This can be handy when checking a graph for being self-dual.
Corrected help message for regular_pl
Removed unneeded code in multi_corona.c
Program to filter graphs in multicode format for being regular
Program to calculate girth of graph in multicode format
Filter for snarks
Added some missing files to source distribution
Program to construct graphs induced by a set of vertices