[Rd] resolving a names conflict

[Therneau, Terry M., Ph.D.]

The survival package uses a generalized cholesky decompostition throughout.  If A is a 
symmetric matrix A= LDL' where L is lower triangular with 1s on the diagonal, D is 
diagonal, and D[i,i] =0 if column i of A is redundant.  Being able to read the rank and 
dependencies directly off of D is very handy.

The bdsmatrix package uses the same, but exposes it to the user as gchol and solve methods 
in the NAMESPACE file.

I'd like to expose it in survival as it would make some current development easier.

How do I do this without causing warning messages for anyone who loads both, e.g., anyone 
using the coxme package?  The S4 structures are identical, but bdsmatrix has a superset of 
methods.   Adding importFrom(bdsmatrix, gchol) is one solution, of course, but it runs 
afoul of the current requirement that recommended packages import only from the core set.

Terry T.