Build typing context - Githubissues

We need a context with all the classes of an application to be able type check our application.

In future, we need to include classes of imported Python files as well.

A typing context has all the relevant types, functions, and fields of the current application.

Add Position and EndPoint structs to pipeline for easy passing of position without having to add a lot of dependencies where they shouldn't be. In effect, positions are abstracted away, which in future should make it easier to create more complex error messages.
Add building of Context based on classes, functions, and fields of script.
- Types which may be inferred at a later date are wrapped in Optionals (in case they are not explicit yet).
- An error is given when there was no type given when there should be one

Rewrite current tests to use new Position struct

JSAbrahams / mamba