Editor plugin system

[Dgzt]

This is a long running PR.

This implements plugin system for editor. The Editor loads plugins from <your_home_directory>/.mundus/plugins directory.

There are 2 new module:

• plugin-api: The plugins should use this module. It contains the necessary extension interfaces.
• editor-commons: This contains the common events what the Editor and plugins use.

Extension interfaces:

• MenuExtension:
  • String getMenuName(): Here can set the name for plugin's menu item in Plugins menu
  • void setupRootDialogWidget(RootWidget): Here can setup the plugin's widget.
• SceneExtension:
  • void sceneLoaded(Array<TerrainComponent>): Here can get the loaded terrain components at scene loaded
• TerrainHoverExtension:
  • void hover(TerrainComponent, Vector3): Here can get the mouse hover position on the terrain.
• StatusBarExtension:
  • void createStatusBarLabel(LabelWidget): Here can create label on statusbar and can set it's label text.
• RenderExtension:
  • RenderableProvider getRenderableProvider(): Here can pass renderable provider to render it on the scene
• EventExtension:
  • void manageEvents(PluginEventManager): Here can subscribe to editor's events.
• DisposeExtension:
  • void dispose(): This method calls in when the Editor disposes its resources.

Subscribable editor events:

• GameObjectModifiedEvent : If a game object has modified
• TerrainAddedEvent: If a terrain has added
• TerrainRemovedEvent: If a terrain has removed
• TerrainVerticesChangedEvent: If the user has changed terrain's shape

TODO list:

• Integrate PF4j dependency into Editor
• Load plugins at editor startup
• The Plugins menu
• A pseudo class to create UI in plugins
• A plugin able to connect to events of editor
• Render plugin on scene
• Remove helper lines

Here is the example plugin: https://github.com/Dgzt/mundus-helper-lines-plugin

[JamesTKhan]

When no plugins are loaded, we get a little weird empty menu pop up. We should probably handle this differently. Maybe a 'No Plugins Loaded' string or something should appear in the menu drop down?

[Dgzt]

When no plugins are loaded, we get a little weird empty menu pop up. We should probably handle this differently. Maybe a 'No Plugins Loaded' string or something should appear in the menu drop down?

Fixed. I've tried to disable 'Plugins' menu if Editor does not have plugins, but seems the VisUI lib doesn't support it.