Offer the possibility to define version compatibility from plugins

app/Core/Plugin/Version.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Kanboard\Core\Plugin;
+
+/**
+ * Class Version
+ *
+ * @package Kanboard\Core\Plugin
+ * @author  Frederic Guillot
+ */
+class Version
+{
+    /**
+     * Check plugin version compatibility with application version
+     *
+     * @param  string $pluginCompatibleVersion
+     * @param  string $appVersion
+     * @return bool
+     */
+    public static function isCompatible($pluginCompatibleVersion, $appVersion = APP_VERSION)
+    {
+        if (strpos($appVersion, 'master') !== false) {
+            return true;
+        }
+
+        $appVersion = str_replace('v', '', $appVersion);
+        $pluginCompatibleVersion = str_replace('v', '', $pluginCompatibleVersion);
+
+        foreach (array('>=', '>', '<=', '<') as $operator) {
+            if (strpos($pluginCompatibleVersion, $operator) === 0) {
+                $pluginVersion = substr($pluginCompatibleVersion, strlen($operator));
+                return version_compare($appVersion, $pluginVersion, $operator);
+            }
+        }
+
+        return $pluginCompatibleVersion === $appVersion;
+    }
+}