Create local todo-list

[gpellicciotta]

Create a simple todo-list based on browser-based local storage.

v1.0.0:

• Add items, delete items + mark them as done

v2.0.0:

• Allow re-ordering items
• Allow adding multiple lists (and choosing the active one to show)

[gpellicciotta]

v1.0.0 is now committed

[gpellicciotta]

Reordering, deleting and local storage now all work.

To fix:

• Use local time i.s.o. UTC
• Don't allow adding empty notes or completely clearing notes
• Ask for confirmation on delete
• Add new items on top
• On mobile: add note on bottom

[gpellicciotta]

All fixed in 2.1.0:

• Don't allow adding empty notes or completely clearing notes
• Add new items on top
• Add note on bottom is now the default UI for non-mobile
• Deleting items now needs to be confirmed (still with ugly UI however)
• Time is local time and relative (e.g. 5 minutes ago)