Fuzzy-asteroids

- Fixed bug in stopping condition for no bullets remaining. Fixed potential initialization error for number of
bullets remaining if it rounded to 0.

- Added stopping condition for when all alive ships are out of ammo. This is done by passing a boolean flag
`stop_if_no_ammo` as an argument to `Scenario()` during instantiation. If this is passed, `ammo_limit_multiplier`
must also be specified or will raise an exception. `ammo_limit_multiplier` can still be active without the
`stop_if_no_ammo` condition however.

- Updated asynch controller calls to be allotted less time proportional to the timestep size. Also suppressed print
statements in `sprites.py`

- Added exception for passing invalid values for the `ammo_limit_multiplier` argument for `Scenario()` instantiation.

- Added functionality for limiting the number of available bullets for each ship based on the total number of
possible asteroids. This is done during scenario creation by invoking an optional argument named
`ammo_limit_multiplier` passed to `Scenario()`. This must be a float that is > 0 and if it is, for example, 1, each
ship will have as many bullets as there are potential separate asteroids. If the argument is not passed during scenario creation,
ships will have unlimited bullets.

- Added more information to the data dictionaries for sprite objects (e.g. team/id values for ships). These
properties, named `data` for each sprite class, can be viewed in `sprites.py`.