bin: overhaul default input selection

If no input have been specified, and the standard input is not a tty all
tools now default to reading it.  If standard input is a tty, all tools
display an error message.  Additionally, - is now a shorthand for -F- in
all tools.

* NEWS: Summarize this.
* bin/common_finput.cc, bin/common_finput.hh (check_no_formulas,
check_no_automaton): New functions that implement the above istty()
logic.
* bin/autfilt.cc, bin/dstar2tgba.cc, bin/ltl2tgba.cc, bin/ltl2tgta.cc,
bin/ltlcross.cc, bin/ltldo.cc, bin/ltlgrind.cc: Use these function,
and recognize '-' if it was not the case.
* tests/core/acc_word.test, tests/core/ltldo.test,
tests/core/minusx.test, tests/core/readsave.test,
tests/core/unambig.test: Adjust some tests to exercise this.
* doc/org/autfilt.org, doc/org/csv.org, doc/org/dstar2tgba.org,
doc/org/ltl2tgba.org, doc/org/ltlcross.org, doc/org/ltlfilt.org,
doc/org/oaut.org: Adjust the documentation and simplify some
examples.

bin/ltlgrind.cc

@@ -189,8 +189,7 @@ main(int argc, char* argv[])
 
   mut_opts |= opt_all;
 
-  if (jobs.empty())
-    jobs.push_back(job("-", true));
+  check_no_formula();
 
   mutate_processor processor;
   if (processor.run())