Contexts

[terrylyons]

I think contexts should be mentioned in the initial read me.

Several first questions I have:

How do I convert a lie element to a tensor?

How do I return the log signature to degree 5 of an interval for a stream initially constructed (via the readme approach) using level 2 increments and areas?

How do I construct a stream based on lie increments and time stamps at the times these increments arrive?

How do I set the coefficient type to rational. What are the current options?