translate: use compositional suspension on request
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.