Move toHTML into html.js
Use underscore, not microscore, in Meteor blaze
Define HTML.isArray
Use refactored html.js in "old" ui-package Blaze

Some failing tests, which are hopefully mostly just tests of the modified code that need to be ported.

The main work was replacing the use of pseudo-attributes $special and $dynamic with the new HTML.Attrs(...) / array representation.  Some functions were also rewritten to use Visitors (`toJS`, old `toHTML`/`toText`/`evaluateAttributes`, `replaceSpecials` in the compiler, but not `optimize` yet or `materialize`).

Create the "blaze-tools" package to hold toJS and other functions that are useful for template parsers/compilers that need to read or generate JS.