Replaces references to indexOf(_:) with index(of:).
Replaces references to indexOf(_:) with index(of:).

The global function `indexOf(_:)` was replaced with
`Collection.index(of:)` in Swift 2.

jawwad/swift-algorithm-club,hollance/swift-algorithm-club,raywenderlich/swift-algorithm-club,jawwad/swift-algorithm-club,raywenderlich/swift-algorithm-club,raywenderlich/swift-algorithm-club,jawwad/swift-algorithm-club