Add call to expose variables declared with Eval

[firelizzard18]

Proposal

I want a function that lists all of the global variables in package main. Specifically, I want a list of variables declared with Eval("var x = 1") and Eval("y := 1").

// Globals returns a map of global variables and constants in the main package.
func (*Interpreter) Globals() map[string]reflect.Value

Background

I have developed an extension that implements Yaegi-based notebooks for Visual Studio Code. I want to add a variables view, like the Jupyter extension has for their notebooks.

Workarounds

I don't think there are any. I was going to show a horrible hack using the debugging interface, but I don't think that exposes global variables. The Symbols function only returns exported values.