Issue with DocBook XML copy removal

[Albert Astals Cid]

Hi, as part of the project that aims to remove DocBook XML copies from 
kdelibs, we have found a small issue with backwards compatibility.

As explained in old mails, the aim of the project is removing DocBook XML 
V4.1, V4.1.2 and V4.2 copies in kdelibs and use an externally provided V4.2.

This means that when compiling against KDE 4.5, any kde docbook using V4.1.2 
docbooks will fail to be generated.

Most of the documentation on the KDE repo was already using V4.2 so i 
understand external programs will mostly copy and paste the correct header 
from our documentation and will be fine after the change. For those using 
older versions on 99.99% of the cases the fix is simply updating the header of 
the docbook (one liner), but we wonder if this change can be considered a 
"source compatibility" problem, in my opinion we only promised source 
compatibility on the "code" level, but others might disagree, hence this mail.

As a side note i want to mention that me, Luigi and Burkhard (not involved in 
the project per se, but KDE documentation master in my book) agree this is a 
"cheap" price to pay for the benefit of freeing us from the embedded copies of 
DocBook XML.

Comments?

Albert