ltlcross: report exit_status and exit_code columns in CSV and JSON

* src/bin/ltlcross.cc: Report exit_status and exit_code columns in CSV
and JSON files.  Also output lines for failed translations, and add
a --omit-missing option to disable that.  Move the time column right
after exit_status and exit_code.
* src/bin/man/ltlcross.x: Document each column of the output.
* bench/ltl2tgba/tools: Use the "{name}cmd" notation.
* bench/ltl2tgba/sum.py: Adjust to the new columns.
* bench/ltl2tgba/README: Update to point to the man page for a
description of the columns.
* bench/ltl2tgba/Makefile.am: Build results.pdf as said announced in
README.
* bench/spin13/html.bottom: Update code to ignore these two new
columns and lines with null values.
* src/tgbatest/ltlcross3.test: Add tests.
* doc/org/ltlcross.org: Adjust examples.
* NEWS: Mention this.

bench/ltl2tgba/Makefile.am

@@ -34,9 +34,11 @@ OUTLOG = $(OUTPUTS:=.log)
 CLEANFILES = $(OUTCSV) $(OUTJSON) $(OUTLOG) \
              results.pdf results.aux results.log results.tex
 
-.PHONY = run
+.PHONY = run json
 
-run: $(OUTJSON)
+run: results.pdf
+
+json: $(OUTJSON)
 
 deps = $(srcdir)/tools \
        $(top_srcdir)/configure.ac \