Allow disable htmlparser plugin (#643)

* allow disable htmlparser plugin

* rename `allow-htmlparser.js` to `__allowHtmlparser.js`

* fix filename typo

* allow override by imported plugins

---------

Co-authored-by: Ivan Paramonau <i.paramonau@gmail.com>

Author: nleush

lib/loader/pluginLoader.js

@@ -283,11 +283,12 @@
             // ID.
             pluginDeclaration.id = getFileName(bits[bits.length - 1]).toLowerCase();
             if (pluginDeclaration.id in plugins) {
-                if (CONFIG.CUSTOM_PLUGINS_PATH && pluginPath.indexOf(CONFIG.CUSTOM_PLUGINS_PATH) > -1) {
+                if (pluginPath.indexOf('node_modules') > -1 
+                    || (CONFIG.CUSTOM_PLUGINS_PATH && pluginPath.indexOf(CONFIG.CUSTOM_PLUGINS_PATH) > -1)) {
                     console.error("Plugin '" + pluginDeclaration.id + "' overridden by", pluginPath);
                     delete plugins[pluginDeclaration.id]
                 } else {
-                    console.error("Duplicate plugin id (filename)", pluginPath);
+                    console.error("Duplicate plugin id ignored (filename)", pluginPath);
                     return;
                 }
             }

lib/plugins/system/htmlparser/__allowHtmlparser.js

@@ -0,0 +1,15 @@
+
+export default {
+
+    provides: [
+        // Run for all who requests htmlparser or meta.
+        'htmlparser',
+        '__allowHtmlparser'
+    ],
+
+    getData: function() {
+        return {
+            __allowHtmlparser: true
+        };
+    }
+};

lib/plugins/system/htmlparser/htmlparser.js

@@ -16,7 +16,7 @@ export default {
         '__statusCode'
     ],
 
-    getData: function(url, whitelistRecord, options, __noCachedHtmlparserFallback, cb) {
+    getData: function(url, whitelistRecord, options, __noCachedHtmlparserFallback, __allowHtmlparser, cb) {
 
         var options2 = {...options, ...{
             followRedirect: !!options.followHTTPRedirect,