ltlgrind: fix handling of FILENAME/COL

This additionally fixes #107.

* src/bin/ltlgrind.cc: Fix handling for FILEANAME/COL.  Document FORMAT
in --help.  Assume -F for arguments given without options.
* src/tests/ltlgrind.test: Add two tests.
* NEWS: Mention this.

src/tests/ltlgrind.test

@@ -22,13 +22,18 @@
 
 set -e
 
-checkopt()
+checkopt_noparse()
 {
     cat >exp
     run 0 ../../bin/ltlgrind --sort "$@" > out
+    diff exp out
+}
+
+checkopt()
+{
+    checkopt_noparse "$@"
     # The result must be parsable
     ../../bin/ltlfilt out
-    diff exp out
 }
 
 checkopt -f 'Xp1 U (p4 | (p3 xor (p4 W p0)))' <<EOF
@@ -181,3 +186,14 @@ F({p2[*2][:*]}[]-> Xp2)
 F({{1;p0}[:*]}[]-> Xp0)
 F({{p2;1}[:*]}[]-> Xp0)
 EOF
+
+echo '1,a,3' > input
+checkopt_noparse input/2 <<EOF
+1,0,3
+1,1,3
+EOF
+
+checkopt_noparse -F input/2 --format '%<,%f,%>,%F,%L' <<EOF
+1,0,3,input,1
+1,1,3,input,1
+EOF