SELF Downloader request

[devnoname120]

Since this feature is in the pipes, I've a few requests to make:

• The user agent should contain some keyword like henkaku to allow the remote website to serve some special content.
• The http/https prefix should be optional. For example, somehomebrew.download should be a valid link, provided it serves a SELF.
• It should be possible to have the SELF run with unsafe permissions.