Remove _authors and _drafts directories

[caendesilva]

We don't really utilise them at this stage, so they can be removed to reduce clutter.

We can still use the author yml system, but move the file to the config directory.

Users who want the drafts directory can just create it as it is not used by Hyde anywhere. "Drafts" can also currently be made by using a different file extension, including .markdown which is ignored by Hyde while still having IDE support.

Tasks:

• Remove _drafts directory
• Rework author yml system
• Remove _data directory.

[caendesilva]

Working on this now in these branches

https://github.com/hydephp/framework/tree/48-remove-_authors-and-_drafts-directories
https://github.com/hydephp/hyde/tree/fr48removecontentdirectories