Add Function and Nil types

[dinkelspiel]

This pull request adds Function types Function0 (no arguments and a return), Function1 (1 argument and a return), Function2 (2 argument and a return) and so on all up to 6 arguments and a Nil type.

Example output for function type

types.IsFunction3(
    types.IsString, // Argument 1
    types.IsString, // Argument 2
    types.IsString, // Argument 3
    types.IsResult(types.IsString, types.IsString), // Return
),

Example output for Nil type

types.IsNil

[darky]

Nice! Thanks!

[darky]

4.3.0