Add demo script and "eat my own dogfood" for process info lookups

Added a simplistic demo script called "show-memory-delta" that loops checking
the memory related counters in /proc/meminfo.  It prints a line any time a
counter changes more than 10% between iterations.

Also, change the "pid_to_proc_summ" routine to use handlers from this package
to pull process info.  The original version ran a "ps" command and captured
the output.