travis: added PhpStan

Author: dg

.travis.yml

@@ -41,6 +41,17 @@ jobs:
                 - php temp/coding-standard/ecs check src tests --config temp/coding-standard/coding-standard-php71.yml
 
 
+        -   stage: Static Analysis
+            php: 7.1
+            install:
+                # Install PHPStan
+                - travis_retry composer create-project phpstan/phpstan-shim temp/phpstan --no-progress
+                - travis_retry composer install --no-progress --prefer-dist
+
+            script:
+                - php temp/phpstan/phpstan.phar analyse --autoload-file vendor/autoload.php --level 5 src
+
+
         -   stage: Code Coverage
             php: 7.2
             script:
@@ -51,6 +62,7 @@ jobs:
 
 
     allow_failures:
+        -   stage: Static Analysis
         -   stage: Code Coverage