Feature: Add EKI specification for EKI standard, a slightly updated IKI standard.

Feature: Add EKI specification for EKI standard, a slightly updated IKI standard.

Think of EKI as an extended IKI.
This introduces a single change (and its accompanying requirements).

Multiple IKI Vocabularies are now supported.
I have been using IKI in practice for a while now.
A need has risen up where I really want to be able to easily designate multiple IKI Vocabularies for a single IKI Variable.

This new format allows for me to do something more similar to HTML.
I have been using IKI as part of a templating process.
With EKI, unlike IKI, I can now make something both bold and italic.
Whereas with IKI, I would have to create a new type that combines them (like `bold_italic`).

I would then have to create two types if I wanted to be order agnostic, such as `bold_italic` and `italic_bold`.
This would get progressively worse if I added a third or more Vocabularies.

With EKI, I don't add any new IKI Variables and the order does not necessarily matter.

Example: `bold:italic:"My example"` (and `italic:bold:"My example"`).
This would have `bold` and `italic`.
The order should be preserved in case something does care about order.
The order can be ignored if something does not care about order.