remove tgba_explicit variants and the old scc_filter

* src/tgba/tgbaexplicit.cc, src/tgba/tgbaexplicit.hh: Delete.
* src/tgba/Makefile.am: Adjust.
* src/tgbaalgos/reductgba_sim.cc, src/tgbaalgos/reductgba_sim.hh:
Delete these obsoleted algorithms.
* src/tgbaalgos/Makefile.am: Adjust.
* src/tgbatest/explicit.cc, src/tgbatest/explicit.test,
src/tgbatest/explicit2.cc, src/tgbatest/explicit2.test,
src/tgbatest/explicit3.cc, src/tgbatest/explicit3.test:
Delete.
* src/tgbatest/Makefile.am: Adjust.
* src/bin/ltl2tgba.cc, src/priv/countstates.cc,
src/tgbaalgos/isweakscc.cc, src/tgbaalgos/lbtt.cc,
src/tgbaalgos/ltl2tgba_fm.cc, src/tgbaalgos/minimize.cc,
src/tgbaalgos/minimize.hh, src/tgbaalgos/powerset.cc,
src/tgbaalgos/powerset.hh, src/tgbaalgos/sccfilter.cc,
src/tgbaalgos/sccfilter.hh, src/tgbaalgos/simulation.cc,
src/tgbatest/explprod.cc, src/tgbatest/ltl2tgba.cc,
src/tgbatest/powerset.cc, src/tgbatest/tgbaread.cc,
src/tgbatest/tripprod.cc, wrap/python/ajax/spot.in,
wrap/python/spot.i: Remove all remaining references to
tgba_explicit.

wrap/python/ajax/spot.in

@@ -700,9 +700,6 @@ if degen or neverclaim:
 else:
     degen = automaton
 
-if utf8:
-    spot.tgba_enable_utf8(degen)
-
 # Buchi Automaton Output
 if output_type == 'a':
     if buchi_type == 'i':