[horde] upgrade horde_prefs identities

[Chris Flav]

>> Are there upgrade scripts to allow an upgrade from H2/IMP3 to H3/IMP4 and then eventually H4/IMP5?
>
>Yes, but you cannot do this in one step. You need to upgrade step-by-step through intermediate versions and follow the upgrade instructions for each version individually.

In other words I download all of the horde* and imp* for versions between the ones used and installed and do all upgrades?  I don't suppose there is a single horde ChangeLog file I could look at?

I will investigate this.  I had found an upgrades/ directory in the H3 install that is on the newer installation and I guess I assumed all the upgrade scripts were already in it.

C Flav