* src/bin/randaut.cc: Replace the --acc-type and --acc-sets
options by a more general --acceptance option, that take either
an acceptance formula, or an acceptance name parametred by ranges.
Also accept a range for the number of atomic propositions.
* src/twaalgos/randomgraph.cc (random_acceptance): Move...
* src/twa/acc.cc, src/twa/acc.hh (random): ... here.
(parse_acc_code): Generalize to accept ranges instead of
numbers whenever sensible, and accept a 'random' acceptance.
* src/tests/randaut.test: Adjust tests and add more.
* wrap/python/tests/randaut.ipynb: Adjust call to randaut.