update kate docbooks to reflect the split off of syntax highlighting to frameworks

Review Request #129880 - Created Jan. 24, 2017 and submitted - Latest diff uploaded

Burkhard Lück
docs, kate
bump date + releaseinfo in katepart
adapt to changes using the frameworks syntax-highlighting (no *xml installed, compiled into a library)
fix location of language.xsd, afaik no longer installed

some questions still remain, see FIXMEs in diff:

* location of custom syntax-highlighting definition files on Windows?

* validation of custom *.xml syntax-highlighting definition files works using "validatehl.sh mySyntax.xml" ?
  you need language.xsd running validatehl.sh but both validatehl.sh + language.xsd are not installed building syntax-highlighting
  and only available in the syntax-highlighting repo on commits.kde.org