model.matrix for tt() terms

look at printCoefmat

pyears with an I() term on the right hand side, "tform" is wrong.

update penalized models
terms for cox.zph, it also needs to ignore NA coefficients.
add design of the survival library document to vignettes

include.lowest for tcut (first find out what the issue is)

add "fun" to summary.survfit
 
?Surv claims that -Inf is allowed, but survreg chokes.

