Update to Swift 4.2.

Author: SpacyRicochet

Red-Black Tree/RedBlackTree.playground/Contents.swift

@@ -2,11 +2,6 @@
 // Test for  the RedBlackTree implementation provided in the Source folder of this Playground
 import Foundation
 
-// last checked with Xcode 9.0b4
-#if swift(>=4.0)
-print("Hello, Swift 4!")
-#endif
-
 let redBlackTree = RedBlackTree<Double>()
 
 let randomMax = Double(0x10000000)

Red-Black Tree/RedBlackTree.playground/playground.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>