Turn on whole module optimizations

After turning this optimization level on, I observed an average decoding
time of 1.611s from 2.523s and an average parsing time of 1.724s from
2.384s.

Argo.xcodeproj/project.pbxproj

@@ -1207,7 +1207,6 @@
  PRODUCT_NAME = Argo;
  SDKROOT = appletvos;
  SKIP_INSTALL = YES;
- SWIFT_OPTIMIZATION_LEVEL = "-Onone";
  TARGETED_DEVICE_FAMILY = 3;
  TVOS_DEPLOYMENT_TARGET = 9.0;
  };
@@ -1435,6 +1434,7 @@
  MTL_ENABLE_DEBUG_INFO = NO;
  RUN_CLANG_STATIC_ANALYZER = YES;
  SDKROOT = iphoneos;
+ SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
  TARGETED_DEVICE_FAMILY = "1,2";
  VALIDATE_PRODUCT = YES;
  VERSIONING_SYSTEM = "apple-generic";
@@ -1461,7 +1461,6 @@
  PRODUCT_BUNDLE_IDENTIFIER = "com.thoughtbot.$(PRODUCT_NAME)";
  PRODUCT_NAME = Argo;
  SKIP_INSTALL = YES;
- SWIFT_OPTIMIZATION_LEVEL = "-Onone";
  };
  name = Debug;
  };