Added reposition before the start of a game

[wellme]

Things I wanted to do but didn't:

• Hide the enemy team in fog (Should be fairly straightforward once Fog of war bugfixing #154 gets merged, don't want to mess with it on this branch in case of conflicts), this prevents the player from reacting to the enemy's unit placement, which would reward stalling during repositioning.
• Add an indicator that a player/team is ready and in position
• Add a good-looking animation for units being swapped
• Add an indicator that shows which unit is currently selected (IIRC, square under the selected unit is shown orange instead of blue
• Use a less HACK HACK HACK way of showing which tiles are spawn points (Currently, it uses a Zone.ZoneType.MOVE_DARK, which looks okay I guess, but it could be a lot better)

The PR also introduces the OverworldInspectionContext, which is just a CursorContext that automatically manages the zones/unit information when hovering a unit. I didn't actually check if other contexts could inherit it to centralize the inspection behavior. Also: I forgot about OverworldContext.onInspectInventory. I'll fix this when I have the time.