Allow WindRose/TimeSeries to accept arbitrary input columns

[paulf81]

Allow WindRose/TimeSeries to accept arbitrary input columns

Presently, the new WindRose/TimeSeries classes accept a fixed set of input signals (wd,ws,ti,price). Would like to augment this with a list of a arbitrary signals which are then shaped and passed as ti,price are now.

Checklist:

• Develop code to allow arbitrary time series to be assigned if they're passed
• Might break attrs rules, need to discuss what is the best approach (@bayc has experience with multidim tables)
• Update tests
• Add documentation

[misi9170]

We have decided that this is not critical functionality for v4; Milestone v4.1 is appropriate.