adding templates.js

dead-simple template system.
`_` is the data-structure (arbitrary json) root.
support is included for evaluating inline JS operations, as well as
using the return statements from IIFEs or otherwise fired functions

Decisions on how to implement loops or branching/conditional views is
still undecided, as well as the elegance of offering such code in the
views.
So IIFEs for now -- eventually, I would prefer code-behind, based on
data-attributes (a la Angular), which is my preference, but making that
work in the traditional format will require some mulling