Make it possible to have a MFA transport

[mmzeeman]

Added the possibility to add MFA's as transport mechanism.

The reason for this is that when you add a fun as transport, it can become a badrun when the module it originates in undergoes code upgrades. This can result in session crashes. This is prevented by using an MFA.

[mworrell]

So also no Pid anymore?

[mmzeeman]

So also no Pid anymore?

Oh, I didn't want to remove that. I'll double check.

[mmzeeman]

Ah, no. I re-used the callback type which includes a pid. It is defined like this:

-type callback() :: pid() | {module(), atom(), list()}.
-type transport() :: function() | callback().

[mworrell]

Ah, then I overlooked that on my phone :-) Thanks for checking!