org: Make sure ../../src/bin is searched first.

We used to set PATH in emacs, but because babel executes "sh" via
shell-command, the configuration of the main shell may supersedes ours.

* doc/org/ltl2tgba.org, doc/org/ltl2tgta.org, doc/org/ltlcross.org,
doc/org/ltlfilt.org, doc/org/randltl.org, doc/org/tools.org,
doc/org/genltl.org: Move all local-file variable to...
* doc/org/.dir-locals.el: ... here.  And also set the PATH
in org-babel-sh-command.
* doc/org/init.el.in: Set the PATH in org-babel-sh-command.

doc/org/.dir-locals.el

@@ -3,6 +3,17 @@
 	 (require-final-newline . t)
 	 (mode . whitespace)))
  (org-mode . ((whitespace-style face empty trailing)
+	      (eval .
+		    (progn
+		      (setq org-babel-sh-command (concat "PATH=../../src/bin"
+							 path-separator
+							 "$PATH sh"))
+		      (org-babel-do-load-languages 'org-babel-load-languages
+						   '((sh . t)
+						     (python . t)
+						     (dot . t)))))
+	      (org-confirm-babel-evaluate . nil)
+	      (org-babel-python-command . "/usr/bin/python3")
 	      (org-publish-project-alist
 	       . (("spot-html"
 		   :base-directory "."