remove args from trigger
provide space for multiple triggers
add ability to store multiple triggers at once
remove set_methods_as_triggers and allow the trigger method to take method names

Previously, in order to write your trigger methods with the def keyword, you'd declare set_methods_as_triggers
Now, you may alter your methods by passing their names to the trigger method.
def a_method; end
trigger :a_method

This will be the same as using trigger with a block
trigger :a_method do; end

But in Ruby 2.0 you'll recieve a symbol after defining a method so you may also do
trigger def a_method; end