This bunch of commits represents work in progress on inlining and
worker/wrapper stuff.

Currently, I think it makes the compiler slightly worse than 4.04, for
reasons I don't yet understand.  But it means that Simon and I can
both peer at what is going on.

* Substantially improve handling of coerces in worker/wrapper

* exprIsDupable for an application (f e1 .. en) wasn't calling exprIsDupable
  on the arguments!!  So applications with few, but large, args were being dupliated.

* sizeExpr on an application wasn't doing a nukeScrutDiscount on the arg of
  an application!!  So bogus discounts could accumulate from arguments!

* Improve handling of INLINE pragmas in calcUnfoldingGuidance.  It was really
  wrong before