Tank shapes (including serialization/deserialization)

[narc0tiq]

At the moment, tanks are fixed boxes (and they used to be just flying text). We need a format for storing tank shape in memory, as well as a serialization format. This will almost certainly be a common module like edicomm.

[narc0tiq]

Revisions starting at ad9d7a9 have been working on this problem by defining the base shapes a tank is composed of.

At the moment (as of d84b52b), these are still just in-memory formats.