Optional Chaining Operator

[Clashsoft]

Add a new operator that allows safe optional chaining.

Example:

let opt: String? = "test"

let upper = opt.toUpperCase // error
let upper = opt == null ? null : opt!!.toUpperCase // verbose

let upper: String? = opt?.toUpperCase // optional access

let firstUpper: char? = opt?.toUpperCase?[0] // multiple optional accesses can be chained