Deprecate PartialFunction.apply
Deprecate PartialFunction.apply

PartialFunction.apply causes confusion because at first glance it looks
like a general purpose factory method for creating PartialFunctions, but
it is only meant to convert ordinary to partial functions (with
`pf.isDefinedAt(x) == true` for all x). When used in the wrong way it
can have confusing semantics.

lrytz/scala,scala/scala,lrytz/scala,scala/scala,scala/scala,martijnhoekstra/scala,lrytz/scala,martijnhoekstra/scala,martijnhoekstra/scala,martijnhoekstra/scala,lrytz/scala,lrytz/scala,scala/scala,martijnhoekstra/scala,lrytz/scala,martijnhoekstra/scala,scala/scala,scala/scala