Add an 'Exists' method to return a bool representing whether or not a key exists

[kbirk]

I have a use case in which the existence of a particular attribute determines how I interact with the parsed JSON.

While the functionality is technically there:

// fields
_, exists = jsonParsed.Search("myProperty").Data().(float64)
if exists {

}
// objects
_, err = jsonParsed.Search("myObjProperty").ChildrenMap()
if err == nil {

}
// arrays
_, err = jsonParsed.Search("myArrProperty").Children()
if err == nil {

}

I think it would be convenient to have a simple and unified interface for doing so:

if jsonParsed.Exists("myPath", "to", "myProperty") {

} 

[Jeffail]

Hey @kbirk,

I've just checked in 785f0ec. Thanks for raising this and sorry for the wait!