Description of requested feature:

Handle drag&drop event for Mudlet package files.

Expected result of feature

1. Drag and drop an mpackage/xml file onto the Mudlet window.
2. Mudlet will automatically install it.
3. No need to fiddle with package manager menus, popups, etc.

Reasons for adding feature:

Make it easier for players to add packages to their Mudlet.

Extra information, such as Mudlet version, operating system and ideas for how to solve / implement:

Also enable this as standard for new Mudlet profiles.

As discussed here: #3484 (comment)