small release: author- and source-level metrics, better filters ux

[Jason Priem]

New features up today:

• cleaner Add Filter interface
• author-level metrics: h-index, i10-index
• source-level metrics: h-index, i10-index, 2yr mean citedness

Those last two should,  of course, be Used Responsibly, particularly the "2yr mean citedness" which applies the same basic methodology as the Impact Factor, though of course based on our (open) data rather than that of Clarivate. But we've had lots of requests for these and we think they have value in helping users transition from legacy toll-access databases.

As always, please send us your feedback, gripes, delights, ideas, and more!

j