edje: Make state index optional

edje: Make state index optional

This shouldn't break stuff, just make things easier.  Think of all that lost
time " 0.0".  Not anymore.  Not even in Embryo scripts.  Indexes should only
be provided when you need them (which is quite rare).

Note that if you use ``set_state("new state")'' in your Embryo scripts, the
produced .edj files will be incompatible with older versions of Edje.  This
backwards incompatibility only applies to Embryo scripts; edje_cc will
generate a ``0.0'' value if the index is omitted from state declarations and
programs.

Sachiel said this patch was OK; our benevolent release manager acked as
well. Blame them if this breaks stuff.

git-svn-id: http://svn.enlightenment.org/svn/e/trunk/edje@73424 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33