Import - todo.sh

- Wrote a todo.sh parser based on Gina's specs.
- Started unit tests (not finished).

scripts/add-ons/README

@@ -1,16 +0,0 @@
-External Scripts
-----------------
-
-Add-on scripts are executed via an alias mechanism in taskwarrior.  This has the
-effect of this command:
-
-    task <script> <arguments>
-
-resulting in the ultimate execution of:
-
-    <script> <arguments>
-
-All external scripts are treated in the same manner, and have no access to the
-taskwarrior internals.
-
----