Allow the precompiler to generate source maps when the srcFile parameter is passed.
This refactors large chunks of the code generation pipeline, allowing metadata to be associated with code chunks as well as breaking out much of the code generation logic into a separate helper.
All helper calls will have access to `options.name` which is the first id value of the mustache operation.
As part of this the helperMissing call has been simplified to remove the indexed name in order to optimize the call. This is a breaking change.
Fixes#634
The idea is that the environment wraps up the mutable stuff in
Handlebars (like the helpers) and that you could theoretically create a
new one at any time and pass it in to Handlebars.template.
Every test makes a new environment and uses it in template compilation.
kpdecker
Tom Dale
Jesse Ezell
Yehuda Katz