sh:  Implement lone tilde expansion

Josh Juran <jjuran@metamage.com>:
	Thanks lewellyn!  I've normalized the whitespace, and I'm saving the
	~username changes for later.
[NEW] tilde.t:  Test lone tilde expansion in sh

Josh Juran <jjuran@metamage.com>:
	Thanks for the tests!  Unfortunately, #8 is based on broken behavior
	in sh and fails in Unix shells.  I fixed the test and rebased onto a
	commit that fixes the issue in sh.
archive.pl:  Ship tilde.t
Merge branch 'sh-lone-tilde'