Adds Paul Graham's Five Commands to task hints

I'm keen for this to be considered for inclusion in todo.txt-android as I feel distributed cognition tools are great for productivity however can lead to errors of omission and that this might be a [helpful nudge](http://en.wikipedia.org/wiki/Nudge_(book\)) towards fuller, more satisfying lifestyles.

An additional task hint is added:

```
Don't ignore your dreams +life
Don't work too much @work
Say what you think +life
Cultivate friendships @anywhere
Be happy +life
```

In a similar spirit to:

```
Take the road less traveled @Woods
Make all the difference +Life
```

This is based on Paul Graham's [The Top of My Todo List](http://paulgraham.com/todo.html) Five Commands, where he inverts five errors of omission identified by a palliative nurse from her experience of the regrets of the dying.