Add some non-working tests.. more tocome.
Add tests for ttr.board/claim-route.

This is by far the most involved/complicated function in the code
base, and so 1). is in greatest need for refactor, and therefore 2). is
in most need of tests.
Refactor tests to use existing functions.

Several of the tests were using `dosync` directly, which I am trying to
establish as an anti-pattern, even (especially!) in tests. This means
that the existing state-modifying functions (`reset-route!`,
`deck-set!`, etc.) should be used instead.

This also meant writing `ttr.board/claim-route!`, which takes a
route/edge map and a player map, and updates a route's `claimed` state
to true, and the `by` state to the player map.
Ensure `discard-deck` is reset by `build-decks`.
Nest the ttr.board-test functions in defn.

Wrapping them in `deftest` resulted in potentially confusing test
output.