Add Travis config

Author: dmvdbrugge

.travis.yml

@@ -0,0 +1,30 @@
+language: php
+
+dist: xenial
+
+matrix:
+  fast_finish: true
+  allow_failures:
+    - php: nightly
+  include:
+    - php: 7.1
+    - php: 7.2
+    - php: 7.3
+    - php: nightly
+
+sudo: false
+
+cache:
+  directories:
+    - "$HOME/.composer/cache"
+
+env:
+  - COMPOSER_NO_INTERACTION=1
+
+install:
+  - travis_retry composer install --no-suggest
+
+script:
+  - composer validate --strict
+  - find src -name *.php | xargs -n 1 php -l
+  - vendor/bin/php-cs-fixer fix --dry-run