[kde-doc-english] katepart doc split

[T.C. Hollingsworth]

The Great KatePart Doc Split has been committed to the frameworks branch!

The old kwrite doc is gone and replaced with the new katepart doc
(which looks awfully similar ;-).  All content not specific to kate
was moved from the kate doc into the katepart doc and replaced by
links.

To compile the new katepart doc, you'll need a recent build of
kdoctools from git (at least up to 5af7fdb).  With that version it
passes checkXML5 and compiles with meinproc5 successfully.

I guess the kwrite Help button goes nowhere now, would a dev mind
changing it to point at "help:/katepart"?  Wasn't quite sure how to do
that properly.  (Or even if khelpcenter is working with KF5 right
now...)

Anyway, please have a look and make sure I didn't mess anything up.
:-)  If it all looks good, I'll go ahead and move it over to
ktexteditor.git in a few days.

Thanks!
-T.C.