begin streaming before running selection setup

[simonpcouch]

There's a slight delay between clearing all of the current selection and streaming beginning to fill the selection in:

Currently, the addin clears the selection, calls $stream(), and then starts the generator. What if we called $stream(), cleared the selection, and then start the generator instead?

[simonpcouch]

Related to #15.

[simonpcouch]

The delay we see here is actually the package's .onLoad() loading available pals. Once that's happened once, this is much snappier.