i can understand that we shall never rescue Exception!

since we shall never rescue SignalException...
fixed a bug where rescuing exceptions from requiring config

just make Rib::API.format_error a module_function, i guess
it's fine...
[rib/more/edit] default editor to vim, and you could override it
add rib/extra/paging and update README.md accordingly

hope this would make the README.md more readable and useful.