[Examples description]
compute_cones.cpp: this example computes the cone boundaries given the number of cones
   and the initial direction.

theta_io.cpp: this example constructs a Theta graph exactly with an input file containing a vertex list,
   and then generates the Gnuplot files for plotting the constructed Theta graph.

dijkstra_theta.cpp: this example constructs Theta graph first and then calculates
   the shortest paths on this graph by calling the Dijkstra's algorithm from BGL.
