Value space consumption optimization (#7)

Using a union to minimize memory footprint for all the different types of a
value.

Adding support for structs (#6)

Structs are little more tricky and I'm sure there are some serious limitations
with memory management. But this is just an experiment...

Adding support for maps (#5)

Works with any key or value type and provides access to these types.

Added keys() and get_key() respectively.

Adding support for arrays (#4)

Adding Type (#3)

Create a proper `Type` type that will make more complex types possible later.

Create ci.yml (#2)

- Add the GitHub action to run tests
- Add install instructions to README

Create LICENSE (#1)

Create simple values for runtime checking