build: don't execute packaging on npm install

Fixes #217

Closes #260
refactor: use Object.create polyfill

Closes #262
refactor: use pratt parser for if expressions
fix(expressions): correct lexer behavior for operators not separated by a whitespace
fix: bind | operator functions to proper 'this'
fix(expression): expr with [] are now assignable

Expressions like `foo[bar]` were considered as non assignable.
Fix now turn assignable all of these examples

`foo[bar]`
`foo.bar[baz]`
`foo[bar].baz`

Fixes #266
Closes #267
feat: allow objects with the 'apply' method in pipe expressions

Closes #268
fix(expressions): observing algorithm adjustements
fix(expr/manipulator): setValue now eval both...

...the left and the right part of the expression.

Closes #270
refactor: use Pratt's parser in {foreach} expressions

Closes #269
docs(playground): Export to Plunker

Allows to export and edit the actual editor content to [plunker](http://plnkr.co)

Closes #276
feat(expressions): add support for the new operator

Closes #273
feat(expressions): add support for multi-statement expressions
refactor: use Pratt's parser for expressions in the {log} block
feat(expressions): support assigment = operator

Closes #272
fix: runtime filescope was wrongly renitialized

The filescope injected by the compiler inside the template function was properly retrieved during initialization.
But then, the variable being wrongly defined as a closure variable, it was reinitialized and not reassigned on subsequent calls.