Pull request to support Mac OS X (and NetBSD) in the mega-test by increasing its shell portability

This changes the mega-test to support contributors on Mac OS X (recognizably, they are legion).

Presumably this will resolve issue #236.

Not having a Mac, since Mac OS X was developed ultimately from BSD Unix, I developed these changes on an Amazon AWS instance running NetBSD (version 6.0).

Now, the mega-test successfully completes, both on NetBSD in the NetBSD shell (which differs from BASH) and on Linux in the BASH shell. Generally, this should increase its portability and (presumably) improve its operability on Mac OS X.

Gem r_a_c's tests continue to pass both on Linux and NetBSD as well.

References:
[Mac OS X history](http://en.wikipedia.org/w/index.php?title=OS_X&oldid=565555321#History)
[NeXTSTEP description](http://en.wikipedia.org/w/index.php?title=NeXTSTEP&oldid=564657111#Description)