POD updates
Minor Makefile.PL, testfile udpates.
Minor change in use arg's: -e [optinal name], -b [optinal name] allow exporting both exercise and benchmark with alternate names; drops -n switch (which only handles one of them).
Split into separate modules for benchmark, execute operation. Avoids loading benchmark module if it won't be used; pushed common variables and utility subs into separate module.
eval use Time::HiRes then Benchmark qw( :hireswallclock ). If that fails then use Benchmark without the hireswallclock.
Require Benchmark-1.07, which handles issues with missing Time::HiRes properly.
Remove begin hacks for dealing with missing Time::HiRes.