When a recipe wraps cli tool and the tool exits with a non-zero code,
just adds its own extra exit error message along with the messages
from the tool. Introduce the `[no-exit-message]` attribute to suppress
this additional message.
Add a new setting "skip-comments", which defaults to true. If unset,
this causes lines internal to a non-shebang recipe beginning with the
character '#' (including '#!' internal to a non-shebang recipe; that is,
any such instances occurring after the first line of a recipe) to be
treated as comments of the justfile itself. They will not be echoed to
stderr when the recipe executes.
