ENH: Sentence delimiters for append action.

This fixes a personal annoyance.
If the text to be appended to the task begins with one of the delimiter characters, no whitespace is inserted in between. This makes appending to an enumeration (todo.sh add 42 ", foo") syntactically correct.
The list of delimiters is configurable (for personal preferences / non-English languages) via SENTENCE_DELIMITERS in the config file.

tests/t1600-append.sh

@@ -44,4 +44,33 @@ test_todo_session 'append error' << EOF
 10: No such task.
 EOF
 
+cat > todo.txt <<EOF
+notice the daisies
+EOF
+test_todo_session 'append of current sentence' <<EOF
+>>> todo.sh append 1 ", lilies and roses"
+1: notice the daisies, lilies and roses
+
+>>> todo.sh append 1 "; see the wasps"
+1: notice the daisies, lilies and roses; see the wasps
+
+>>> todo.sh append 1 "& bees"
+1: notice the daisies, lilies and roses; see the wasps & bees
+EOF
+
+cp todo.cfg special-delimiters.cfg
+cat >> special-delimiters.cfg <<EOF
+export SENTENCE_DELIMITERS='*,.:;&'
+EOF
+test_todo_session 'append of current sentence SENTENCE_DELIMITERS' <<EOF
+>>> todo.sh -d special-delimiters.cfg append 1 "&beans"
+1: notice the daisies, lilies and roses; see the wasps & bees&beans
+
+>>> todo.sh -d special-delimiters.cfg append 1 "%foo"
+1: notice the daisies, lilies and roses; see the wasps & bees&beans %foo
+
+>>> todo.sh -d special-delimiters.cfg append 1 "*2"
+1: notice the daisies, lilies and roses; see the wasps & bees&beans %foo*2
+EOF
+
 test_done

todo.sh

@@ -469,6 +469,12 @@ 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 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
+# (todo.sh add 42 ", foo") syntactically correct.
+export SENTENCE_DELIMITERS=',.:;'
+
 [ -e "$TODOTXT_CFG_FILE" ] || {
     CFG_FILE_ALT="$HOME/todo.cfg"
 
@@ -746,9 +752,13 @@ case $action in
     else
         input=$*
     fi
+    case "$input" in
+      [$SENTENCE_DELIMITERS]*)  appendspace=;;
+      *)                        appendspace=" ";;
+    esac
     cleaninput $input
 
-    if sed -i.bak $item" s|^.*|& $input|" "$TODO_FILE"; then
+    if sed -i.bak $item" s|^.*|&${appendspace}${input}|" "$TODO_FILE"; then
         [ $TODOTXT_VERBOSE -gt 0 ] && {
             newtodo=$(sed "$item!d" "$TODO_FILE")
             echo "$item: $newtodo"