Profile Sqitch to Identify Performance Bottlenecks

[theory]

Sqitch is slow. And not just because it talks to the database. I suspect it's slow mainly because of Moose constraints. But we should profile it to be sure.

Best approach is probably to run the test suite with Devel::NYTProf. And if Moose is in fact the problem, maybe see about the feasibility of switching to Moo.

[theory]

Switched from Mouse and Moose to Moo in dbb22bd for another 40% or so speedup on startup. This merge also defers the loading of DateTime until it's needed, because it loads all the locales it can, which is an additional overhead.

[theory]

Performance is much better with Moo. If necessary, we can look into other possible performance improvements:

• Figure out how to get DateTime to load only the locales it needs.
• Eliminate most Moo isa parameters, and therefore the overhead of type-checking. Maybe find a way to keep it turned on when the $HARNESS_ACTIVE environment variable is set?

[theory]

Gonna call this one done. DateTime is an independent fix, and the switch to Moo was a huge improvement. We can revisit in the future, but no need to keep tracking it for 1.0.