Bumping to 0.3

Bumping to 0.2.1.

0.2 (#8)

0.2.0
* Adds support for archetypes with `Vec`-like dynamic storage capacity. This can be used by setting the keyword `dyn` as the capacity value in the `ecs_archetype!` declaration. Worlds generated by `ecs_world!` now have a `with_capacity` function with arguments for each dynamic archetype to pre-allocate storage. 
    * Fixed-capacity archetypes won't have arguments in `with_capacity` -- they are always allocated to their full fixed capacity on world creation.
    * Resolves #3 
* Adds an `Entity<_>` pseudo-parameter to queries. This will match any archetype like `EntityAny`, but will yield a typed `Entity<A>` for the currently-matched archetype in the query body.
* Adds a new `32_components` crate feature to go up to 32 maximum components in a single archetype. Enabling this feature may impact compile times.

Touch up and polish on docs. Bumping to 0.1.0