Stubble extensions and enhancements

Thoughts on standards and differences

When building Stubble one of the things I set out to avoid was the situation that Nustache, the precursor to Stubble, got itself into by adding non-standard mustache functionality by default. It could be quite easy for users to fall into using these non-standard components and then you've inadvertently made your templates pinned to the library you're using and if things get changed in future the version.