elm theme use - use elementary only for themes and remove e's own theme

elm theme use - use elementary only for themes and remove e's own theme

now e only uses elementary's theme. this is to stop the bitrot and
forking of e's theme vs the unified elm theme that has everything for
e in it already. this obviously makes elm a requirement of e18 on, and
this also notes that emotion is always in efl these days, so its no
longer an option, and ecore-imf is no longer used as edje does the
entires now itself. in future it'll all be elm.

this is a major unification point for themes for elm and e. this will
need some testing, but everything seems to work day-to-day, but theme
selector is untested.

this also removes the theme selector for splash as that is now simply
unified with the same theme as everything else.