[Ifeffit] Mac Installer

[Matt Newville]

Hi Paul,

You could definitely do it with Applescript.  Being a more comfortable
with unix than applescript, the main thing that I relied on with
Applescript was that it could run a bash script.   So each applescript
prorgram runs /Applications/Ifeffit/bin/iff_init.sh to set its
environment variables.    It would be very easy to add a line to run a
perl/python/bash program from iff_init.sh that checked for updates.   
That's how I would do it, but if you're more comfortable using
Applescript, that's great.  The current scripts are very primitive and
could probably use many enhancements!

The flow you have looks right to me, but I would suggest that
interacting with a real installer is not completely necessarry.   It
could simply download and unpack a zip or tar.gz file containing new
versions of files to put in /Library/Perl and/or /Applications/Ifeffit
paths.  Again, that's what I'd do, but having it be more Mac-like is
fine with me.

--Matt