Rewrite main function to use reduce

In order to make the top interface more declarative
i'm building the html file using reduce
using an object as a memo and functions as items.
On each reducing step, i'm calling each of the
functions, which do their job and save some data
in the object memo.

The object holds the data needed to create the html file
and that object is augmented on each function.

In order to be easily composable, each function takes
the same arguments: the accumulated invoiceObj and
the asyncCallback we need to use to go to the next step.
Add a scrapbook dir for tests
Change order