Plugin manager for enabling/disabling plugins

Go to About Plugins and enable/disable plugins from there.

Reviewed-by: mae

src/libs/extensionsystem/optionsparser.cpp

@@ -128,8 +128,7 @@ bool OptionsParser::checkForNoLoadOption()
                                                              "The plugin '%1' does not exist.").arg(m_currentArg);
             m_hasError = true;
         } else {
-            m_pmPrivate->pluginSpecs.removeAll(spec);
-            delete spec;
+            m_pmPrivate->removePluginSpec(spec);
             m_isDependencyRefreshNeeded = true;
         }
     }