These routines free the 'struct command': a common coding error is not
to return immediately.
To catch this, we make them return a non-NULL 'struct command_result
*', and we're going to make the command handlers return the same (to
encourage 'return command_fail(...)'-style usage).
We also provide two sources for external use:
1. command_param_failed() when param() fails.
2. command_its_complicated() for some complex cases.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I want to use param functions in plugins, and they don't have struct
command.
I had to use a special arg to param() for check to flag it as allowing
extra parameters, rather than adding a one-use accessor.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
