added command-line utilities for defining input arguments of the driver.py and for walking the given input directory and collecting all plt files found within
Full path of plt files are now populated in the plt file list
error code if given directory does not contain plt files
Added output directory parameter, and automatically created the output directory if it does not exist
added function to extract user ID from plt file path
Randomly selecting 20 plt files and converting to staypoints, named according to the originating PLT file and the user.
instead of writing files out with .plt suffix, write out as .txt suffix