docbook_3-3.1-160000.2.2

- Modernise spec file a bit
- Rename docbook_3-README.SuSE to docbook_3-README.SUSE

- remove several other URLs (which are no longer available at
  the old address or elsewhere)

- fix URL of dbhset.tar.gz (no longer available at the old HTTP
  address or elsewhere).

- fix URL of source archives

- Fixup installed CATALOG files to follow the move to /usr/share.

- Replace old $RPM_* shell vars and "useless use of cat".

- Do not install in /var/lib; bsc#1093345

- update license to new format

- iso_ent is required for SGML, so readd it as long as SGML is supported

- No longer require iso_ent (now Recommends).