new readline application hook to print macro key sequences and values; change bind -X default output format; bind -x accepts more input formats; quoting changes for pathname expansion patterns

tests/comsub2.right

@@ -166,3 +166,20 @@ argv[1] = <AA>
 argv[2] = <BB>
 argv[1] = <AA BB>
 argv[1] = <AA BB>
+inside1-inside2-outside
+BEFOREAA
+BB
+CC
+AFTER
+BEFOREAA
+BB
+CC
+AFTER
+unbalanced braces}}
+combined comsubs
+combined comsubs
+inside
+after: var = inside
+after: 42 var = inside
+var=inside 42
+after: 0 var = inside