Multiple cleanups

- Use upstream version 20121211 to indicate that it's a git snapshot,
  rather than a released version from upstream.
- Do not close bug #1234 just to silence a Lintian warning
- Minor fixes to short/long Description
- Minor cleanups to the manpage
- Drop elfutils build-dependency as it's superfluous
- Remove /usr/share/dpkg/default.mk include from debian/rules
- Do not use quotes for setting DEB_CXXFLAGS_MAINT_APPEND &
  DEB_OBJCXXFLAGS_MAINT_APPEND as these are passed to GCC.