travis: added PhpStan

Author: dg

.travis.yml

@@ -44,6 +44,17 @@ 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
             script:
                 - vendor/bin/tester -p phpdbg tests -s --coverage ./coverage.xml --coverage-src ./src
@@ -53,6 +64,7 @@ jobs:
 
 
     allow_failures:
+        -   stage: Static Analysis
         -   stage: Code Coverage