update compare_results tool to use recently renamed result files
reformat the docstrings
document the meaning of box_table() elements
output documentation for the per-box statistics
remove SVN keywords
output documentation if no argument supplied
edited the command line documentation
convert zontotext to output GHCN-M v3 format

and reformat docstrings
remove SVN keywords
add the --box argument to whatstations
improve error message in zontotext
fix bug: ZON files have 16 records
move maskpng.py to github.com/drj11/islscp2landmaskpng