statez 0.1.2

Basic state management for the ggez game framework.
# Introduction

statez provides basic state management for [ggez](https://crates.io/crates/ggez).
`StateManager` is a wrapper for `ggez::event::EventHandler`. It keeps track of
`State`s in a stack and passes events received to the topmost (i.e. active)
`State`. Data can be shared between `State`s.

`State::update()` should return a `StateTransition` that tells the
`StateManager` what should happen next.

# Examples

- [`hello_world`][hw]: The simplest example of switching between two states.
- [`using_shared_data`][sd]: An example of a) two
  states accessing shared data and b) a state allowing previous states to be
  drawn underneath it by returning true in State::draw_previous_state().

[hw]: examples/hello_world.rs
[sd]: examples/using_shared_data.rs