Add dropoff creation code

[dgets]

Now that we've got some bots out that are a bit better about spawning and mining, we're ending up with a lot of ships that have almost full halite that are unable to return to the shipyard, due to clogging of the main route & the pawn formation issue (#33). It would be very beneficial to pick those that are congested, and farther away from the shipyard than the others, and create a new dropoff in order to facilitate easier collection of halite.

This will necessitate, at least, the following:

• analysis of the ShipHistory for more than just the last turn, or at least proper turnstamp setting and analysis; however, being as more ShipHistory is going to be required at some point soon, anyway, it'd make sense to just Do It Right(tm) the first time here (or second time, as it were)
• analysis of the game_map in order to determine the proper [full] ship to create a dropoff with; this will be based upon ships surrounding it (at least those in pawn formation and/or full of halite) and distance from the shipyard or other dropoffs
• how long any pawn formation blockade has existed (potentially negating the above factor)
• (at some point) analysis of the closest local maxima to determine if it may be most efficient to create a dropoff anyway

[dgets]

This is a duplicate of issue #14, though there are new factors taken into account. I'm going to close this issue and paste the information above into the existing to avoid duplicates.