Added psalm and php-cs-fixer

composer.json

@@ -18,7 +18,9 @@
         "php-coveralls/php-coveralls": "dev-master",
         "phpstan/phpstan": "0.12.x-dev",
         "phpunit/phpunit": "^8.0|^9.0",
-        "squizlabs/php_codesniffer": "3.*"
+        "friendsofphp/php-cs-fixer": "^2.16",
+        "vimeo/psalm": "^4.00"
+
     },
     "config": {
         "sort-packages": true
@@ -34,6 +36,8 @@
         }
     },
     "scripts": {
+        "psalm": "vendor/bin/psalm --show-info=true",
+        "fix": "vendor/bin/php-cs-fixer fix --allow-risky=yes",
         "test": [
             "XDEBUG_MODE=coverage vendor/bin/phpunit --coverage-clover build/logs/clover.xml --coverage-html build/logs/phpunit-html/"
         ],

psalm.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+<psalm
+    errorLevel="4"
+    findUnusedVariablesAndParams="true"
+    resolveFromConfigFile="true"
+    useDocblockPropertyTypes="true"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+>
+    <projectFiles>
+        <directory name="src"/>
+    </projectFiles>
+
+    <issueHandlers>
+        <NoInterfaceProperties errorLevel="suppress"/>
+    </issueHandlers>
+
+    <plugins>
+    </plugins>
+</psalm>