ENH: Added highlighting of done (but not yet archived) tasks.

This makes done tasks more stand out (like prioritized tasks) in the task list. Default highlighting is LIGHT_GREY, which seems to be modest and go well with the assumed dark terminal background.
Reintroduced the OSX-compatible sed filter that was introduced by commit 8b7e2e6aad and superseded by the PRI_X coloring generalization.

tests/t1330-ls-highlighting.sh

@@ -111,4 +111,41 @@ test_todo_session 'different highlighting for pri X' <<'EOF'
 TODO: 8 of 8 tasks shown
 EOF
 
+# check highlighting of done (but not yet archived) tasks
+#
+cat > todo.txt <<EOF
+(A) smell the uppercase Roses +flowers @outside
+remove1
+notice the sunflowers
+remove2
+stop
+EOF
+test_todo_session 'highlighting of done tasks' <<EOF
+>>> todo.sh -a do 2
+2 x 2009-02-13 remove1
+TODO: 2 marked as done.
+
+>>> todo.sh list
+1 (A) smell the uppercase Roses +flowers @outside
+3 notice the sunflowers
+4 remove2
+5 stop
+2 x 2009-02-13 remove1
+--
+TODO: 5 of 5 tasks shown
+
+>>> todo.sh -a do 4
+4 x 2009-02-13 remove2
+TODO: 4 marked as done.
+
+>>> todo.sh list
+1 (A) smell the uppercase Roses +flowers @outside
+3 notice the sunflowers
+5 stop
+2 x 2009-02-13 remove1
+4 x 2009-02-13 remove2
+--
+TODO: 5 of 5 tasks shown
+EOF
+
 test_done

todo.cfg

@@ -38,18 +38,26 @@ export TMP_FILE="$TODO_DIR/todo.tmp"
 # export WHITE='\\033[1;37m'
 # export DEFAULT='\\033[0m'
 
-# === PRIORITY COLORS ===
+# === COLORS ===
 
-## Priorities can be any upper-case letter.
-## A,B,C are highlighted; you can add coloring for more.
 ## Uncomment and edit to override these defaults.
-
+## Reference the constants from the color map above,
+## or use $NONE to disable highlighting.
+#
+# Priorities can be any upper-case letter.
+# A,B,C are highlighted; you can add coloring for more.
+#
 # export PRI_A=$YELLOW        # color for A priority
 # export PRI_B=$GREEN         # color for B priority
 # export PRI_C=$LIGHT_BLUE    # color for C priority
 # export PRI_D=...            # define your own
 # export PRI_X=$WHITE         # color unless explicitly defined
 
+# There is highlighting for tasks that have been done,
+# but haven't been archived yet.
+#
+# export COLOR_DONE=$LIGHT_GREY
+
 # === BEHAVIOR ===
 
 ## customize list output

todo.sh

@@ -470,6 +470,9 @@ export PRI_B=$GREEN         # color for B priority
 export PRI_C=$LIGHT_BLUE    # color for C priority
 export PRI_X=$WHITE         # color for rest of them
 
+# Default highlight colors.
+export COLOR_DONE=$LIGHT_GREY   # color for done (but not yet archived) tasks
+
 # Default sentence delimiters for todo.sh append.
 # If the text to be appended to the task begins with one of these characters, no
 # whitespace is inserted in between. This makes appending to an enumeration
@@ -531,6 +534,7 @@ if [ $TODOTXT_PLAIN = 1 ]; then
     done
     PRI_X=$NONE
     DEFAULT=$NONE
+    COLOR_DONE=$NONE
 fi
 
 _addto() {
@@ -632,6 +636,9 @@ _list() {
             s/^ /0/;
           ''' \
         | eval ${TODOTXT_SORT_COMMAND}                                        \
+        | sed '''
+            /^[0-9]\{'$PADDING'\} x /s|^.*|'$COLOR_DONE'&'$DEFAULT'|
+          ''' \
         | awk '''{
             pos = match($0, /\([A-Z]\)/)
             if( pos > 0 && match($0, /^[0-9]+ x /) != 1 ) {