Support {{#.}} and Iterable values
Support arbitrary getters in templates via reflection

Based on the mustache4dart implementation.

https://github.com/valotas/mustache4dart/blob/ce0bc54960f5c54b734ac5b4731837c550f69ac6/lib/src/mustache_context.dart#L84
Attempt #2 at reflection
Add import for dart:mirror
Update to new analyzer