Various cleanups

Based on !1, please review/merge that first.

• !1

• d/rules: Use the correct --bindir

  This doesn't currently matter, because we don't run make install and the binary doesn't hard-code its own path, but in principle it could matter in a future version.

• d/gbp.conf: Add

  This ensures that team uploads and NMUs use pristine-tar, following what the maintainer did.

• d/rules: Use DEB_CPPFLAGS_MAINT_APPEND instead of DEB_CPPFLAGS_APPEND

  The former is reserved for packaging/maintainer use, and the latter is reserved for users doing a modified rebuild.

  Thanks: Lintian

• d/rules: Use the upstream make install in the conventional way

---

I also downloaded hannah_2.0.1+ds1.orig.tar.gz from the archive and pushed corresponding pristine-tar metadata to the pristine-tar branch.