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.

tests/core/readsave.test

@@ -115,9 +115,8 @@ diff stdout stdout2
 # exercise both %M and %m.  The nonexistant file should never be
 # open, because the input stream is infinite and autfilt should
 # stop after 10 automata.
-randltl -n -1 a b |
-    ltl2tgba -H -F - |
-    autfilt -F- -F nonexistant --states=3 --edges=..10 --acc-sets=1.. \
+randltl -n -1 a b | ltl2tgba |
+    autfilt -F - -F nonexistant --states=3 --edges=..10 --acc-sets=1.. \
 	     --name='%M, %S states' --stats='<%m>, %e, %a' -n 10 > output
 cat >expected <<EOF
 <F(b | Ga), 3 states>, 5, 1
@@ -278,7 +277,7 @@ autfilt --merge -Hm input --name="%E->%e edges, %T->%t transitions" > output
 diff output expected
 
 
-cat <<EOF | ltl2tgba -x degen-lskip=1 -F- --ba -H > tmp.hoa
+ltl2tgba -x degen-lskip=1 --ba > tmp.hoa <<EOF
 a U b
 false
 !b && Xb && GFa