Descent tracked hoard orbs by borrowing the player's proximity bomb
slot. Commit 829e95b6f8 moved proximity
bomb tracking to its own slot, but failed to update the player
death/deres logic accordingly. This caused multiple inconsistencies
when a player was killed in hoard mode:
- The killed player saw the orb drop as expected.
- The killed player _also_ kept the orb in inventory after respawn,
because the counter was not reset.
- Other players saw no orb drop.
Fix the inappropriate retention by resetting the orb count in
init_player_stats_new_ship. Fix the inappropriate failure to drop by
adding a new unconditional field to the player death/deres message. In
hoard games, use it to pass the orb count. In other games, ignore it.
Fixes: 829e95b6f8 ("Separate hoard/proximity tracking")
Reported-by: snytek <https://github.com/dxx-rebirth/dxx-rebirth/issues/526>