BUG: Multiple whitespace was condensed, CR/LF not turned to space.

Missing quoting inside cleaninput() condensed multiple subsequent spaces into a single space, even when the user took pains to preserve whitespace by properly quoting the task in the shell.
The 'tr' command completely removed CR and LF characters instead of replacing them with a single space.
Add test cases for the whitespace handling to the add, append, prepend and replace actions.

tests/t1000-addlist.sh

@@ -77,4 +77,37 @@ TODO: 5 added.
 TODO: 5 of 5 tasks shown
 EOF
 
+#
+# Advanced add
+#
+
+cat /dev/null > todo.txt
+test_todo_session 'add with spaces' <<EOF
+>>> todo.sh add "notice the   three   spaces"
+1 notice the   three   spaces
+TODO: 1 added.
+
+>>> todo.sh add notice how the   spaces    get lost
+2 notice how the spaces get lost
+TODO: 2 added.
+
+>>> todo.sh list
+2 notice how the spaces get lost
+1 notice the   three   spaces
+--
+TODO: 2 of 2 tasks shown
+EOF
+
+cat /dev/null > todo.txt
+test_todo_session 'add with CR' <<EOF
+>>> todo.sh add "smell the
+Carriage Return"
+1 smell the Carriage Return
+TODO: 1 added.
+
+>>> todo.sh list
+1 smell the Carriage Return
+--
+TODO: 1 of 1 tasks shown
+EOF