This function takes in standard nan-separated arrays (such as for a coastline), and draws them onto Google Earth.

It can also handle a single lon/lat track that has no NaN values (such as a ship or airplane track).

Syntax:
KML_LINE(LON, LAT) writes nan-separated lines specified
in LON and LAT to an output file, doc.kml
KML_LINE(LON, LAT, NAME) writes nan-separated lines specified
in LON and LAT to an output file, NAME.kml
KML_LINE(LON, LAT, NAME, COLOR) writes lines same as above but with
MATLAB color value (default is 'w').
KML_LINE(LON, LAT, NAME, WIDTH) writes lines same as above but with
width WIDTH (default is 1).
KML_LINE(LON, LAT, NAME, COLOR, WIDTH) writes lines same as above but
with width WIDTH and color COLOR.

Input:
LON: 1-D array of longitude line values. Separate lines are separated
by a NaN. Must correspond to LAT.
LAT: 1-D array of latitude line values. Separate lines are separated
by a NaN. Must correspond to LON.
NAME: String name of output file (without the .kml extension)
COLOR: MATLAB color (default is 'w'), supports vector colors.
WIDTH: int or float width value (default is 1)

Output:
This function creates a kml file called NAME.kml in the current
working directory

Examples:
% four different ways of calling kml_line:
load('palau_coastline.mat');
kml_line(lon_coast, lat_coast, 'palau_coastline');
kml_line(lon_coast, lat_coast, 'palau_coastline', 'r');
kml_line(lon_coast, lat_coast, 'palau_coastline', 1.5);
kml_line(lon_coast, lat_coast, 'palau_coastline', 'm', 2);