Be more robust against unknown entry types

Right now when an unknown entry type is encountered, we can end up
appending a NULL value in the middle of the entry list, which might
later result in a segfault in the client dereferencing NULL when
iterating the list.
Be more robust to that error, so that the returned entry list is always
composed of valid elements.

https://bugzilla.redhat.com/show_bug.cgi?id=872884

https://bugzilla.gnome.org/show_bug.cgi?id=693353
Prepare 0.0.3
Post-release version bump
build: Don't install INSTALL

Really, no one needs this on their system in the first place.  But I'm
specifically deleting it because it broke in the gnome-ostree build
system; automake may have it be a symlink, and we don't want to
install that.

https://bugzilla.gnome.org/show_bug.cgi?id=706137
build: Fix srcdir != builddir

The enum files are potentially in $(builddir), not $(srcdir); we
should be able to just rely on Make's VPATH handling to DTRT.

https://bugzilla.gnome.org/show_bug.cgi?id=706137
build: Fix enum generation

First, drop the conditional on maintainer mode; we shouldn't rely on
--enable-maintainer-mode to build the enums from git.

Second, rework the style to fix srcdir != builddir, and avoid weird
hardcoded tempfile names.  This newer style can be found in the
gnome-shell git for example.

https://bugzilla.gnome.org/show_bug.cgi?id=706137