loosen slightly the requirements for changing existing chars

in the c:x;r;a keystroke

original commit: fce4cbad3a6dcd68b182a7bcf9dd38df2d92356e

collects/framework/private/dir-chars.rkt

@@ -1,6 +1,7 @@
 #lang racket/base
 (require racket/list)
 (provide adjustable-chars
+         double-barred-chars
          up-chars
          dn-chars
          lt-chars
@@ -36,4 +37,8 @@
 
 (define adjustable-chars
   (remove-duplicates
-   (append up-chars dn-chars lt-chars rt-chars)))
+   (append up-chars dn-chars lt-chars rt-chars)))
+
+(define double-barred-chars
+  (remove* '(#\+ #\- #\|) 
+           adjustable-chars))