14 // Adds metadata option to add chunks to metadata

[stuartjohnpage]

connects to #14

Overview

• Adds in an option to add additional metadata to every chunk, in the form of a map with a custom key/value
• Updates the relevant documentation

The thing I don't like about this is the empty metadata property that we now get on chunks. I was toying with either a) doing some fancy macro that can switch up the struct definition, or defaulting it to nil. Or this might actually be a good thing/necessary evil to get the struct definition nice and stable

Either way, please let me know what you think. Is this what you had in mind @gordoneliel?

[stuartjohnpage]

I'm closing this for now, pending discussion in #14