Added phpcs config

Author: ddrv

.gitignore

@@ -1,4 +1,4 @@
-/.idea/*
-/vendor/*
-/phpunit.xml
+vendor/
+phpcs.xml
+phpunit.xml
 composer.lock

phpcs.xml.dist

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<ruleset name="Coding standard">
+    <description>Coding standard</description>
+
+    <!-- display progress -->
+    <arg value="p"/>
+    <!-- use colors in output -->
+    <arg name="colors"/>
+
+    <!-- inherit rules from: -->
+    <rule ref="PSR12">
+        <exclude name="PSR12.Properties.ConstantVisibility.NotFound"/>
+    </rule>
+
+    <!-- Paths to check -->
+    <file>src</file>
+    <file>tests</file>
+</ruleset>