Improve support changes in application name

[andymatuschak]

**Andy Matuschak (andymatuschak)* reported (on Launchpad) on' 2008-05-09:*

Sparkle fails utterly if the application's name changes at some point
through its history. I think the right way to do this is that if the
package to be installed is going to have an unexpected name, set some
attribute in that appcast item. Needs more thought.

This ticket was migrated from the old trac: re #11
Originally reported by: andym

[andymatuschak]

**Hofman (cmhofman)* wrote on 2009-11-20:*

Implementation would be pretty simple. Add a new key to the appcast for
the installation filename and add support for it in SUAppcastItem. Then
add a delegate method for SUInstaller to ask SUBasicUpdateDriver for
this value. When it is supplied, just look for that file rather than the
default guesses based on the host app's name.

[zorgiepoo]

Renaming app bundles right now is kind of cumbersome and complicated with normalization ( SPARKLE_NORMALIZE_INSTALLED_APPLICATION_NAME). And normalization isn't pleasant to maintain support for.

This probably shouldn't be a setting on the appcast item though, but maybe an Info.plist key in the new app.