simplify match() by removing _match() in EventType
clean up seh.rb
remove type accessor from EventType
add event_type_spec
add skeletal event_target_spec
add event_bind_spec
event_type nil now matches everything (instead of nothing)
add EventTarget::Default, a default class mixing in EventTarget;  update event_target_spec
add event_bind_disconnector_spec
add seh_spec
wip refactoring and documenting Event
wip Event
wip Event refactor
update some examples
add a benchmark task to Rakefile
rm Gemfile.lock from .gitignore
add Gemfile.lock
trivial