Adds a new `Binder` struct that traverses the AST and resolves variable
references to concrete `Address` types (Local, Upvalue, Global). This
information is crucial for the Virtual Machine's execution phase.
Introduces the `BoundKind` enum to represent the AST after binding.
The `VM` is updated to handle `BoundKind` nodes and execute the bound
AST.
It now manages a call stack, local variables, and closures for function
calls and upvalue capturing.
The `Environment` struct is enhanced to manage global variables and
provide
a unified interface for parsing, binding, and executing scripts. It also
includes basic standard library functions.
Michael Schimmel