Issue fix: Multiple do items

Can now do multiple items in one go.
Either comma seperated list or a whitespace seperated list

tests/t1500-do.sh

@@ -0,0 +1,72 @@
+#!/bin/sh
+
+test_description='do functionality
+'
+. ./test-lib.sh
+
+#DATE=`date '+%Y-%m-%d'`
+
+test_todo_session 'do usage' <<EOF
+>>> todo.sh do B B
+usage: todo.sh do ITEM#
+=== 1
+EOF
+
+cat > todo.txt <<EOF
+smell the uppercase Roses +flowers @outside
+notice the sunflowers
+stop
+remove1
+remove2
+remove3
+remove4
+EOF
+
+test_todo_session 'basic do' <<EOF
+>>> todo.sh list
+2 notice the sunflowers
+4 remove1
+5 remove2
+6 remove3
+7 remove4
+1 smell the uppercase Roses +flowers @outside
+3 stop
+--
+TODO: 7 of 7 tasks shown from $HOME/todo.txt
+
+>>> todo.sh do 7,6
+7: x 2009-02-13 remove4
+TODO: 7 marked as done.
+6: x 2009-02-13 remove3
+TODO: 6 marked as done.
+x 2009-02-13 remove3
+x 2009-02-13 remove4
+TODO: $HOME/todo.txt archived.
+
+>>> todo.sh -p list
+2 notice the sunflowers
+4 remove1
+5 remove2
+1 smell the uppercase Roses +flowers @outside
+3 stop
+--
+TODO: 5 of 5 tasks shown from $HOME/todo.txt
+
+>>> todo.sh do 5 4
+5: x 2009-02-13 remove2
+TODO: 5 marked as done.
+4: x 2009-02-13 remove1
+TODO: 4 marked as done.
+x 2009-02-13 remove1
+x 2009-02-13 remove2
+TODO: $HOME/todo.txt archived.
+
+>>> todo.sh -p list
+2 notice the sunflowers
+1 smell the uppercase Roses +flowers @outside
+3 stop
+--
+TODO: 3 of 3 tasks shown from $HOME/todo.txt
+EOF
+
+test_done