- make table of contents, footnotes etc. clickable hyperlinks
- use timestamp of techdoc.tex (instead of build time) as creationdate
  in the PDF metadata
- don't include build date on first page of the PDF
- make clean:
  - delete techdoc.out (created by pdftex)
  - fix deletion of techdoc.txt (was techdo_r_.txt)

The initial target was to get reproduceable PDF builds (therefore the 
timestamp-related changes), the other things came up during discussing
this patch with David Haller.

The only remaining difference in the PDF from build to build is the /ID
line.  This line can't be controlled in pdflatex and is now filtered 
out by build-compare in the openSUSE build service (bnc#760867).

Credits go to David Haller for writing large parts of this patch
(but he didn't notice the techdo_r_.txt ;-)


Signed-Off-By: Christian Boltz <apparmor@cboltz.de>