Display custom actual in assertion message

[nwinch]

Hey @moll! I noticed in the assert function here:

if (!("actual" in opts)) opts.actual = this.actual
if (!("caller" in opts)) opts.caller = assert.caller

var msg = stringify(this.actual) + " must " + (this.negative ? "not " : "")

That this.actual is stringified, though could that be stringify(opts.actual) instead? As this.actual is assigned to opts.actual a couple of lines above anyway if it doesn't already exist.

This would help me pass a more pleasant looking actual for the assertion error message, which I'm doing over at must-jsx.

[moll]

Hey! Sure, customizing what gets stringified makes sense. I see there's Must.prototype.throw that uses the actual parameter for assigning to the error object but still expecting the original actual (the function that threw an exception) to be stringified. Once I figure out how these two cases can co-exist, I'll make the change ;)