The Set type is gone. Instead, templates are automatically associated by
being parsed together; nested definitions implicitly create associations.
Only associated templates can invoke one another.
This approach dramatically reduces the breadth of the construction API.
For now, html/template is deleted from src/pkg/Makefile, so this can
be checked in. Nothing in the tree depends on it. It will be updated next.
R=dsymonds, adg, rsc, r, gri, mikesamuel, nigeltao
CC=golang-dev
https://golang.org/cl/5415060
It's already in old/template; make that build.
Update a couple of references to point to the old template.
They can be updated later.
Update goplay to use exp/template.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4902046
