Suppose we have a uniform rectanglular grid as shown below. The `a` is an agent, `o` is obstacle and `g` is goal. What are the options of handling multitile agents (e.g. dragons or tanks)? . . . . o . . . . . . . o . g . . a a . . . . . <-- too tight . a a . o . . . . . . . o . . . . . . . . . . . <-- should go through this gate . . . . . . . . . . . . o . . .