New Functions for JMESPath

[the-g-man]

I'd like to propose a few additional functions for inclusion in the JMESPath specification:

https://github.com/the-g-man/jmespath-ext

They're not complex to implement but they add a great deal of power - for instance in dealing with recursive or normalized data structures.

I've added documentation and compliance tests for each of the three functions.

[jameswilson]

Oooh. The zip function could be really useful for a project I'm currently working on. Nice ideas there @the-g-man