Consistent integration of libraries

[sp1tz]

Currently, the entire 220 library of functions is exposed as a global lib220. However, this is not the case for other libraries where we define separate globals for each of the methods. This scheme presents a tighter coupling between EJS and its libraries, which makes it harder to update them. Also, it unnecessarily pollutes the EJS global namespace.

Ideally, there would be no preset list of globals pertaining the libraries, which would force users to require every EJS library they wanted to utilize. At a minimum for now, we should expose each library as we do for 220, as a standalone single global object reference. This will also necessitate updates to the 220 assignments.

See /src/index.ts for context.