(compilation-auto-jump): Call

(compilation-auto-jump): Call
compile-goto-error only when compilation-auto-jump-to-first-error
is non-nil.
(compilation-scroll-output): Replace :type 'boolean with a choice
that has three options including a third option `first-error'.
Doc fix.
(compilation-start, compilation-forget-errors): Add an alternate
condition comparing compilation-scroll-output with `first-error'
in addition to compilation-auto-jump-to-first-error (to call
compilation-auto-jump in the proper place).