jlnr/gosu — pull request #209 by myokoym (2014-04-20 15:36:45+00:00)
Title: Add init callback to zen

I think that the after is better (more readable and faster) than the before.

before:
```ruby
update do
@x ||= 0
@x += 1
end
```

after:
```ruby
init do
@x = 0
end

update do
@x += 1
end
```