Another bugfix release!

Bugfix release:

• fixes some more memory leaks when handling out-of-memory in get_all()
  function
• improve error reporting when an attribute disappears after we asked
  for its length but before we managed to read it
• fix int/size_t issues found by RedHat/Fedora,
  https://bugzilla.redhat.com/show_bug.cgi?id=1127310; the fix is
  different than their fix, but it should accomplish the same thing
• convert all code to only do explicit casts after checking boundaries,
  making the code -Wconversion-clean (although that warning is not
  enabled by default)