Changes for plottrail.pl script:

0.20    4 Jan 2003
	- lines are drawn in a lighter color than actual points
	- reorganized documentation
	- corrected typos in documentation
	- added more error checking (won't plot if no data)
	- modularized code
	- multiple input files are allowed
	- fixed confused terms between longitude and latitude in some
	  portions of code (embarassing!)
	- commented out assertions in code for coordinate checking

0.10   28 Dec 2002
	- first release
