BuildRequire python-setuptools for SLES11

which ships a python-Pygmentize package which needs python-setuptools at
runtime but doesn't bother listing it in Requires.
Fix broken package on SLES11

It turns out that with SLES11's rpmbuild we can't install into
%{_docdir} because the final rpmbuild phase *removes* that directory
just before copying into it anything listed as %doc.  So we have to
use %doc to package the API Reference and Getting Started docs.  But
There are files in doc/get-start/ which we need *not* to package, like
build products from the example, so we need to use a new intermediate
directory doc/inst/.  Oh what a tangled web.
Don't pass --docdir to configure on SUSE

It turns out that the reason this wasn't done automatically for us was
that it shouldn't be done at all.  We now follow the correct approach
which is to use %doc in the .spec file, so this is not necessary after
all.
Install docs on Debian/Ubuntu too.

Adjust debian.rules for new doc/inst/ intermediate directory.