Update to Swift 4.2 and test on Xcode 10

Author: tonyarnold

.travis.yml

@@ -1,26 +1,27 @@
-osx_image: xcode9.4
+os: osx
+osx_image: xcode10
 language: swift
 env:
     global:
         - LANG=en_US.UTF-8
         - PROJECT="Differ.xcodeproj"
         - SCHEME="Differ"
-        - IOS_SDK=iphonesimulator11.4
-        - OSX_SDK=macosx10.13
-        - TVOS_SDK=appletvsimulator11.4
-        - WATCHOS_SDK=watchsimulator4.3
+        - IOS_SDK=iphonesimulator12.0
+        - OSX_SDK=macosx10.14
+        - TVOS_SDK=appletvsimulator12.0
+        - WATCHOS_SDK=watchsimulator5.0
     matrix:
         - >-
             DESTINATION="arch=x86_64" SDK="$OSX_SDK" SCHEME="$SCHEME"
             RUN_TESTS="YES" BUILD_EXAMPLE="NO" POD_LINT="NO"
         - >-
-            DESTINATION="OS=11.4,name=iPhone 7" SDK="$IOS_SDK" SCHEME="$SCHEME"
+            DESTINATION="OS=12.0,name=iPhone 7" SDK="$IOS_SDK" SCHEME="$SCHEME"
             RUN_TESTS="YES" BUILD_EXAMPLE="YES" POD_LINT="YES"
         - >-
-            DESTINATION="OS=11.4,name=Apple TV 4K" SDK="$TVOS_SDK"
+            DESTINATION="OS=12.0,name=Apple TV 4K" SDK="$TVOS_SDK"
             SCHEME="$SCHEME" RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD_LINT="NO"
         - >-
-            DESTINATION="OS=4.3,name=Apple Watch - 42mm" SDK="$WATCHOS_SDK"
+            DESTINATION="OS=5.0,name=Apple Watch - 42mm" SDK="$WATCHOS_SDK"
             SCHEME="$SCHEME" RUN_TESTS="NO" BUILD_EXAMPLE="NO" POD_LINT="NO"
 script:
     - set -o pipefail

Differ.xcodeproj/project.pbxproj

@@ -351,7 +351,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "com.tonyarnold.$(TARGET_NAME:c99-identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 4.2;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
@@ -373,7 +373,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "com.tonyarnold.$(TARGET_NAME:c99-identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_COMPILATION_MODE = wholemodule;
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 4.2;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				VALIDATE_PRODUCT = YES;
 				VERSIONING_SYSTEM = "apple-generic";

Differ.xcodeproj/xcshareddata/xcschemes/Differ.xcscheme

@@ -29,7 +29,9 @@
       shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
          <TestableReference
-            skipped = "NO">
+            skipped = "NO"
+            parallelizable = "YES"
+            testExecutionOrdering = "random">
             <BuildableReference
                BuildableIdentifier = "primary"
                BlueprintIdentifier = "C9838FF01D29571000691BE8"