Calculus SQ3 Series Definition

[jbunn3]

This is something I'm pretty adamant about, so I have to bring this up. In Definition 8.3.12, we define the limit of a series (a number), and then turn around and define an infinite series to be that number.

I will draft a PR on Monday to clarify the definition of a series as a pair of sequences and create a Remark about common uses (and abuses) of series notation. This change might require some modifications to the rest of the section to improve the flow.

[StevenClontz]

Hm - my personal formaliation of a series is that it's a property of a sequence: the limit of its partial sums. I'm interested to see what your approach is.

[jbunn3]

I think this is closed via #377