Infinite recursion in param resolve

Hi there,

you are most likely aware of this, but I'm filing this as an issue anyway. As you point out in the wiki (https://github.com/linkedin/dustjs/wiki/Dust-Tutorial#Parameter_rules) params will overlay the context with their own "namespace" for resolving themselves if their values are template strings.

This can lead to infinite recursion if a param value string references a context element with the same name as the param key.

Less words, more code: https://gist.github.com/darkspotinthecorner/6564b77cc2e4165a935a

I know, it's a bit contrieve, but maybe it's worth fixing. ;)

PS: Great work here, I really enjoy working with dustjs!

Start with the reproduction linked in the issue and the wiki's Parameter rules section, then locate the parameter-resolution entry point in Dust. Trace the self-referential template-string case and add a regression test showing that it terminates without infinite recursion while preserving normal parameter and context resolution.

Written by the indexing model from the issue text.