Extend Value into the Object type

[rogchap]

Basic casting of a Value to an Object (val.AsObject()) as well as converting Value to an Object (val.Object())

Only covers a small subset of the Object API as described here: https://v8.github.io/api/head/classv8_1_1Object.html

Also includes converting an ObjectTemplate to an Object with a given Context, and retrieving the Global Object from a Context.

This allows for things like this at runtime:

iso, _ := v8go.NewIsolate()
obj, _ := v8go.NewObjectTemplate(iso)
ctx, _ := v8go.NewContext(iso, obj)
global := ctx.Global()
console, _ := v8go.NewObjectTemplate(iso)
logfn, _ := v8go.NewFunctionTemplate(iso, func(info *v8go.FunctionCallbackInfo) *v8go.Value {
	fmt.Println(info.Args()[0])
	return nil
})
console.Set("log", logfn)
consoleObj, _ := console.NewInstance(ctx)
global.Set("console", consoleObj)
ctx.RunScript("console.log('foo')", "")
// Output:
// foo

[codecov]

Codecov Report

Merging #74 (c8e550a) into master (85aad81) will increase coverage by 1.42%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #74      +/-   ##
==========================================
+ Coverage   92.44%   93.86%   +1.42%     
==========================================
  Files           9       10       +1     
  Lines         344      391      +47     
==========================================
+ Hits          318      367      +49     
+ Misses         19       17       -2     
  Partials        7        7              

Impacted Files	Coverage Δ
context.go	93.05% <100.00%> (+0.40%)	⬆️
json.go	100.00% <100.00%> (ø)
object.go	100.00% <100.00%> (ø)
object_template.go	100.00% <100.00%> (ø)
value.go	95.03% <100.00%> (+1.48%)	⬆️

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[zwang]

Nice, will this changes allow getting any object down the object tree and also override to set any object? Probably except overriding Global Object?

[rogchap]

Yes, you should be able to get and set any Object in the tree and the change would be reflected in the VM.
You can change the Global Object too; but do so at your own peril, as you could break the VM.

[tmc]

Only minor comments. LGTM