Allow org-clock-in-switch-to-state to be a function.

Allow org-clock-in-switch-to-state to be a function.

Allow org-clock-in-switch-to-state to be a function. This lets you have
different clocked in states for different TODO keyword sets, for example

(defun ahkt-clock-state (state)
  (cond ((string= state "TOREAD") "READING")
	((string= state "TOWATCH") "WATCHING")
	(t state)))

Also fix indentation on clock lines, and empty clock drawers when they are
inserted.