This has to be turned on using "-x comp-susp" and other
related options documented in spot-x (7).
* src/tgbaalgos/translate.hh, src/tgbaalgos/translate.cc:
Add support for calling composition-suspension, with
optional simulation, WDBA-minimization, and composition.
* src/bin/spot-x.cc: Document the new options.
* src/bin/man/spot-x.x: Add some bibliography.
* src/tgbatest/ltlcross2.test: Test it.
This perform pre- and post-processings in addition to
the LTL-to-TGBA translation.
* src/tgbaalgos/translate.cc, src/tgbaalgos/translate.hh: New files.
* src/tgbaalgos/Makefile.am: Add them.
* src/tgbaalgos/postproc.hh: Make the private part protected, so
that we can inherit from that in the translator class.
* src/bin/ltl2tgba.cc: Use the translator class to hide LTL
simplification, translation, and postprocessings.
* NEWS: Mention it.
