[R] terms.inner() reprise

[Terry Therneau]

 I quickly recieved several replies to my terms.inner question.  To
summarize:

1. "It was never in R"
Clearly I was mistaken in my assumptions.  Since gam used it, and gam was
ported, I assumed terms.inner had to have been in R at some point.  But that
version of gam must never have made it to R.

2. Given #1, it's not too surprising that I didn't (yet) get any answers to the
main question, which is what to do instead.  How do you know what can
replace something, when you've never seen the something, after all.  A
bit more digging on my own found that
	all.vars(delete.repsonse(formula))
seems to be what I want.  Something that returns "x z" from the formula
	y ~ log(x) + cos(z)
	

3. "gam has to attached"
This surprised me.  I think of lm, glm, and gam as the "big 3" models from
the Chambers and Hastie book, in the sense of using them all the time in
my consulting work.  I would never have guessed that the first 2 would
make it into base R and the last not so.  
  If I had downloaded and attached the right thing, it seems that I would have
found print.gam.

4. Hiding names
  The soapbox part of my note is getting the most response, and very
entertaining it is.  getAnywhere() seems to be the most general fix to my
frustration.  I may come back with another note summarizing some of the
philosophical debate.

	Terry Therneau