When calling Pry.start() the specified options are passed to the "when_started"
hook. This makes it possible for plugins (combined with commit
b270761efa) to specify their own options without
causing Pry to wet itself.
Signed-off-by: Yorick Peterse <yorickpeterse@gmail.com>
Also the return value of exec_hook() is now the value of the last executed hook.
Internally, hooks now use arrays (rather than hash). Also added a get_hooks() method.
Updated tests to reflect these changes.
