New texexec very confused

[Mike Bird <mgb@yosemite.net>]

The new ruby texexec is very confused.  The problem of output
defaulting to pdf instead of dvi has already been noted.  Here
are some additional problems:

Command:            texexec --output=dvips foo
Should produce:     foo.dvi
Actually produces:  foo.pdf

Command:            texexec --dvi foo
Should produce:     foo.dvi
Actually produces:  foo.dvi AND OVERWRITES foo.ps

--Mike Bird