A temporary fix for faster module loading

*All* directories and *all* types were being checked, whereas always only the
first was being used.  This quick fix short-circuits search as soon as the
first candidate is found.
Fix for autoviv Typed hash problem

As suggested by jnthn.  I think there is a ticket for this, but do not know
its number.
Fix for "exists" handling on typed hashes

Made in cooperation with jnthn++ and moritz++
Suggested change by jnthn

See http://irclog.perlgeek.de/perl6/2013-05-28#i_7124130 .  Spectested ok.
Add an implementation of Int.msb .

This is mostly just a "something that works" implementation, if
others feel a need to come up with more elegant/faster versions,
feel free to do so.
Add Int.lsb to setting.

Like Int.msb in the previous commit, this is also a
"something that works" implementation.  More elegant or
performant solutions are welcomed.
Merge pull request #145 from lizmat/fastermoduleload

A temporary fix for faster module loading
Merge pull request #146 from lizmat/autovivtypedhash

Fix for autoviv Typed hash problem
Merge pull request #147 from lizmat/existstypedhash

Fix for "exists" handling on typed hashes
make dir() lazy; written while waiting for plane to YAPCNA