Debounce and defer

[geoffhendrey]

Description

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Type of Change

• Bug Fix
• [ x] New Feature
• Breaking Change
• Refactor
• Documentation
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Checklist

• I have read the contributing guidelines
• Existing issues have been referenced (where applicable)
• I have verified this change is not present in other open pull requests
• Functionality is documented
• All code style checks pass
• New code contribution is covered by automated tests
• All new and existing tests pass

[geoffhendrey]

@zhirafovod if you have a chance, a review of this would be great. Nothing deep. If what I put int he readme makes sense, i think we are good. Also, check out the new "--tail until " (you can see it used in readme.md). The design discussion w nachi is captured here: https://confluence.corp.appdynamics.com/display/[email protected]/discussion+of+defer+function
I did a lot of cleanups and refactors in TemplateProcessor.ts. The new functionality is here:
https://github.com/cisco-open/stated/pull/38/files#diff-576871674848cbd1c9f681fed62a7ccb934e54483d9f9284d36cb2c573e8d1bdR1340
It required that the changeCallbacks support multiple callbacks for any given jsonpointer into the document. This was always needed but just never got around to it. Even external users of TemplateProcessor may want 5 different callbacks for differnent purposes to monitor a given piece of the template for change. Actually need to go back and do the same thing for the commonCallback.

[zhirafovod]

Thank you for improving the README and --tail functionality, and linking the design discussion. It really helps!