Move abusehelper.core.shadowservermail out of abusehelper.core

[ghost]

abusehelper.core should probably have as little provider-specific code as possible. Therefore we should move the ShadowServer mail feed bot out.

The bot seems to be so widely used that it's best to keep it in the abusehelper package by creating a subpackage abusehelper.bots.shadowserver. Two things are up in the air:

• Should wait for pull request #6 ("Generalized mail parsing") to land?
• If so, should we provide a limited-time transition wrapper for the bot or just urge people to move straight to the new style of launching mail feed bots (which should not be a huge change)?

[ics]

Waiting for the Generalized mail parsing makes sense. Using deprecation warnings will allow people to take notice and update other mailer bots they might have.

[ghost]

The current plan is to wait until #6 has been merged (probably not in time for 3.0.0) and add deprecation warnings. This can be done in a minor release, as it doesn't break backwards compatibility. Then in a future major release remove core.shadowservermail (and core.imapbot).