Add libogg section rather than checking for it every time it's necessary.

Add optional third value to results() to allow for non "yes" answers which are
considered positive.

Rewrite the liboggflac tests, the m4 macro is way too complicated for no
reason and it's buggy.

This commit adds a new pretty print menu, we've (far) outgrown the old
menu which because hard to traverse.

Ogg Tremor doesn't have the ability to be disabled under the first if
conditional, might as well AC_DEFINE there.

Add Post Decoder Plugins Tests and move things that shouldn't be in individual
tests to it.