GPX file reader

% ROUTE = LOADGPX(FILENAME) Loads route point information from a .GPX
% GPS interchange file. This utility is not a general-purpose
% implementation of GPX reading and is intended mostly for reading the
% files output by the "gmap pedometer" tool.
%
% ROUTE is a Nx6 array where each row is a route point.
% Columns 1-3 are the X, Y, and Z coordinates.
% Columns 4-5 are latitude and longitude
% Column 6 is cumulative route length.
%
% Note that the mapping of latitude/longitude assumes an approximate spherical
% transformation to rectangular coordinates.
%
% Additional property/value arguments:
% LOADGPX(...,'ElevationUnits','meters',...) uses meters for elevation
% LOADGPX(...,'Viz',true,...) displays the route and elevation map
%
% For more information on the gmap pedometer and GPX output:
% http://www.gmap-pedometer.com/
% http://www.elsewhere.org/journal/gmaptogpx/
%
% See also xmlread