add osx support

Signed-off-by: Sean Ogden <positivelyskewed.sf@gmail.com>
Merge branch 'osx' of git://github.com/seanogden/e

* 'osx' of git://github.com/seanogden/e:
  add osx support
Implement "time" in libe rather than header-only to hide portability ugliness.
Add -lrt when necessary