Allow users to replace existing Pencil and private stencil collections with newer versions without having to manually remove the old ones first. Specifically, allow replacing bundled 3rd party collections.
Currently users if users want to install a newer version of a collection, they must remove the old one first. Included collections cannot be removed so they are hardcoded to whichever version was included . This makes bundled 3rd party collections un-upgradeable. We should allow replacing anything... We could simply always ask the user if they wished to replace the existing collection, then delete the collection before continuing with the import or abort the import. Or we could add something like version numbers to collections & allow replacing if the version number is higher. See: [collectionManager.js](https://github.com/prikhi/pencil/blob/develop/app/content/pencil/definition/collectionManager.js#L250-L254)