Add travis config to launch project checks

.travis.yml

@@ -0,0 +1,40 @@
+# TravisCI configuration for polylang/wpml-to-polylang
+
+language: php
+
+os:
+  - "linux"
+dist: "xenial"
+
+cache:
+  directories:
+    - "${HOME}/.composer/cache"
+
+notifications:
+  email:
+    on_success: never
+    on_failure: change
+  slack:
+    rooms:
+      - secure: "Ydrk6ilDyS5ymD1qGnHlRYIyyTNnZjjM2ZS7HK/D0n/FXCWNHeOxPzEiyO2QZ5eEtREuceKGBfPiDe
+      +cG3P4x6kQvS8w8p62hrlMapOJQF2jCxVlczhQmbFgv8FFlKHwyfVhrIGDitDCa+rAzsBRS/cIm6C9YzQ1BQ7zbF2Mfr0c/1hVQ
+      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"
+
+branches:
+  only:
+    - master
+
+jobs:
+  include:
+    - name: PHPCS + PHPStan - PHP 7.4
+      php: 7.4
+      env: WP_VERSION=latest WP_MULTISITE=0
+      install:
+        - composer install
+      script:
+        - vendor/bin/phpcs
+        - vendor/bin/phpstan analyze --memory-limit=400M
+
+before_install:
+  - "phpenv config-rm xdebug.ini"
+  - "export PATH=\"$(composer config --absolute --global bin-dir):${PATH}\""