Add ship selector to filter pilots.
Only add a new row if all other rows have assigned ships.
Fix broken tests.

* `addShip()` wasn't taking into account the part where a new ship row
  appears after a ship type is selected.
Add tests for new ship selector behavior.
Don't die immediately on fail (was for debugging only).
Add view as text test.
Merge branch 'feature/4_ship_selector'

Fixes #4