Put the name of the program in "$whoami" instead of messing with $0.
Use "basename" in the "File::Basename" package to determine the name
of the program.
Whitespace cleanups.
Better usage message.
Add support for "--after" to only look at revisions after the
specified date.
Redo command-line parsing to use "Getopt::Long". Remove previous
parsing of no-op, undocumented "-r" and "-c" options. Removed unused
variables $showauthor, $showchange, $showrev.