Prototype a SHIFT+Click&Drag result selection

[aaronhelton]

Intended to address #1573 et al.

Implements a prototype of a click and drag record selector.

To test: Open speech review and search for something. Holding SHIFT, click a result, hold down the mouse button, and drag to highlight results. Release mouse to check the checkboxes. Send selected to basket.

[aaronhelton]

Possible refinements:

1. Shift may not be necessary for normal select
2. But Shift Click should start a range selector like a standard text selector