Update CI setup

.swift-version

@@ -1 +1 @@
-4.2
+4.2.1

.travis.yml

@@ -6,6 +6,6 @@ sudo: required
 dist: trusty
 osx_image: xcode10
 install:
-    - eval "$(curl -sL https://gist.githubusercontent.com/kylef/5c0475ff02b7c7671d2a/raw/9f442512a46d7a2af7b850d65a7e9bd31edfb09b/swiftenv-install.sh)"
+    - eval "$(curl -sL https://swiftenv.fuller.li/install.sh)"
 script:
-    - ./scripts/CI.sh
+    - swift test -c release -Xswiftc -enable-testing -Xswiftc -DCI -Xswiftc -Xfrontend -Xswiftc -solver-memory-threshold -Xswiftc -Xfrontend -Xswiftc 999999999