[Rd] error checks

[Terry Therneau]

 I'm currently packaging up some of the kinship matrix routines more
formally, these are used in coxme when dealing with family correlation
structures.  One of my test programs exercises error conditions, i.e.,
it purposely feeds particular types of invalid pedigree data in to see
if the right error message results.  So there are comment-action pairs
	# the next line should generate a "pedigree loop" error
	kindepth(.....

As I found out last night, such tests case a failure of R CMD check!
Any suggestions on how to properly package these?

 A second question is keywords.  None of the standard ones apply to this
code -- I'd like "genetics".  How do we add a new one?  

Terry T.