First pass of adding bills to finplan.

We now have a new page /bills that shows any bills on the left-hand side (type, date, amount)
and bill types and some derived values (frequency and annual growth rate) on the right-hand side

The new bill, and new bill type buttons/logic all work
The delete bill and bill type buttons/logic all work

The change bill type logic all works (and is a touch complex, it alters the GUI
to show/hide different buttons, and disable/re-enable content in the bill types
table

THe change bill is disabled for now and for later

BUGS

@@ -0,0 +1,3 @@
+when I remove and re-add a different onclick handler for new-bt and canc-bt, it
+just does not really seem to work.   If I call NewBillType(id) where id > 0, it
+actuall updates in the backend, but it always does NewBillType(0)