Alias prefix on document type folders

[matthewcare]

Proposal:
When creating folders under "Documnet Types" you have the option of providing an alias prefix.

For example:

Here "element" is automatically applied to the generated alias.

This prefix will apply to everything created in that folder, sub folders which also supply a value will take presidence.

I personally prefer prefixing the generated classes with thier designation elementBlaBla, compositionBlaBla, documentTypeHomePage to make file structure a little easier to navigate.

I've already experimented with the viability, and have a good proof of concept of it working, but I was wondering if people would actually find the feature useful. If so I'll finish it up, and open a PR.

[skttl]

I think it could be useful, but what if you move a type from one folder to another, should it then change the alias to match the new folders prefix?

[matthewcare]

Currently once you save a document type the alias no longer auto generates and requires you to manually change it, so I don't think there is any need to handle things like that.