Add a '-l' flag to show CPU load for the various states, similar to what

Add a '-l' flag to show CPU load for the various states, similar to what
"top" does (thinking of it, i could have as well used the same format line!)

This only makes sense when "-w" option is also specified, because the
load is computed as the difference between subsequent samples.

I think this (and the "-d" feature which shows differences in the
network statistics counts) would also make sense in the standard
vmstat and netstat.