Added support for macro and endmacro tags.
Added from tag and made it work with twig.js
Load _self object and if lookup fails then try to load template.
Standardize {% from %} to  {% import %}
update build
Remove _context from macro context
Added tests for macro and import functionality
Added support for {% from template import func as blah %} and testcases.
Merge pull request #137 from iapain/macros

Added macro and import support to twigjs