Make backslash escape "-" in property matches

* lisp/org.el (org-make-tags-matcher): Read "\\-" as "-" in
the tags/property matcher.

Ilya Shlyakhter writes:

> When doing an agenda tags match for tags or properties with dashes in
> their name, the dashes become negation operators: "my-prop>0" means
> "entries that have the tag 'my' and do not have a positive property
> 'prop'", rather than "entries that have a positive property
> 'my-prop'".  Is there a way to escape the dashes to get the latter
> meaning?

lisp/org.el

@@ -12432,7 +12432,7 @@ also TODO lines."
 
   ;; Parse the string and create a lisp form
   (let ((match0 match)
-	(re (org-re "^&?\\([-+:]\\)?\\({[^}]+}\\|LEVEL\\([<=>]\\{1,2\\}\\)\\([0-9]+\\)\\|\\([[:alnum:]_]+\\)\\([<>=]\\{1,2\\}\\)\\({[^}]+}\\|\"[^\"]*\"\\|-?[.0-9]+\\(?:[eE][-+]?[0-9]+\\)?\\)\\|[[:alnum:]_@]+\\)"))
+	(re (org-re "^&?\\([-+:]\\)?\\({[^}]+}\\|LEVEL\\([<=>]\\{1,2\\}\\)\\([0-9]+\\)\\|\\(\\(?:[[:alnum:]_]+\\(?:\\\\-\\)*\\)+\\)\\([<>=]\\{1,2\\}\\)\\({[^}]+}\\|\"[^\"]*\"\\|-?[.0-9]+\\(?:[eE][-+]?[0-9]+\\)?\\)\\|[[:alnum:]_@]+\\)"))
 	minus tag mm
 	tagsmatch todomatch tagsmatcher todomatcher kwd matcher
 	orterms term orlist re-p str-p level-p level-op time-p
@@ -12460,7 +12460,9 @@ also TODO lines."
 	  (setq rest (substring term (match-end 0))
 		minus (and (match-end 1)
 			   (equal (match-string 1 term) "-"))
-		tag (match-string 2 term)
+		tag (save-match-data (replace-regexp-in-string
+				      "\\\\-" "-"
+				      (match-string 2 term)))				      
 		re-p (equal (string-to-char tag) ?{)
 		level-p (match-end 4)
 		prop-p (match-end 5)