Add currency formatting

Rework the dependency relationships to use AMD RequireJS

Full working calculator. Still needs validation and some polish, but it's working

bugfix: escsape on existing row which has been cleard of text now aborts instead of deletes

Add keyboard shortcuts (enter/escape) for commit/cancel. Also do not save empty lineitem

Can add new rows and delete existing rows

Can edit an item, make changes, save. Uses the renderer to model the render

A basic, partially functional, UI. I want to try this differently though.

Working line item calculator with example in app.js