Documentation needs some improvement

[Robert Ramey]

Basically the whole library is quite good. But I have a couple of minor complaints.

a) The documentation contains sentences like:

"iterator begin();

Get the iterator pointing to the beginning of the circular_buffer. 

I think the refers to the current front of the queue - where ever that falls in the underlying storage. This I could use this iterator to iterate from the oldest item to the most recent item. Naturally the value returned by this function call would change as items are popped of the queue. But it could also refer to the begin (and end) of underlying storage. I don't think it does this - but it's not clear from the documentation.

b) I would also like to have a constructor which allows me to pass any pair of random access iterators (ie. a range) and have the circular buffer use that rather than allocating it's own storage. This would make the package more useful to me and i would hope others as well.

Robert Ramey