ClosestFrontier: Particle Mapping using global inputs

This code moves particles in a 2D map using global commands to discover all boundaries/frontiers.

ClosestFrontier is a demonstration of mapping a completely connected
and bounded 2D discrete grid space with k particles that move uniformly.
The permissible moves are left, right, up and down. Each move is one pixel
in length. All particles move in the same direction unless stopped by
black obstacles.
This algorithm for motion planning moves the particles in red to frontier
cells in blue until no frontier cells remain.
Inputs: k= number of particles, itr= number of iterations
outputs: movecount= number of moves taken for mapping, k= number of
particles and nodecount= vector with number of frontier cells in each
move.
The DIJKSTRA distance is calculated in each cycle to find the shortest
distance from all particles to the frontiers.
There are 33 maps to choose from: 1 through 22 being
created through matrices and 24 through 33 being image read maps.
Map specifications can be found in blockMaps.m and selected by G.mapnum
A demonstration can be viewed in the link below.
https://youtu.be/-rUVmLkd9Oc
Authors:
Aaron T. Becker
[e-mail]
Arun Mahadev
[e-mail]
Edited by: Daniel Bao
[e-mail]