Add variable colors-enable-rainbow-delimiters to colors layer

By default the value is `nil`

contrib/colors/config.el

@@ -14,8 +14,16 @@
 ;; Prefixes 
 ;; ---------------------------------------------------------------------------
 
-(setq spacemacs/key-binding-prefixes '(("C" .  "colors")
-                                       ("Ci" . "colors-identifiers")
-                                       ("tC" . "toggles-colors")))
+;; Variables
+
+(defvar colors-enable-rainbow-identifiers nil
+  "If non nil the `rainbow-identifers' package is enabled.")
+
+;; Command prefixes
+
+(setq colors/key-binding-prefixes '(("C" .  "colors")
+                                    ("tC" . "toggles-colors")))
+(when colors-enable-rainbow-identifiers
+  (push (cons "Ci" "colors-identifiers") colors/key-binding-prefixes))
 (mapc (lambda (x) (spacemacs/declare-prefix (car x) (cdr x)))
-      spacemacs/key-binding-prefixes)
+       colors/key-binding-prefixes)

contrib/colors/packages.el

@@ -15,12 +15,14 @@
     ;; not working well for now
     ;; rainbow-blocks
     rainbow-delimiters
-    rainbow-identifiers
     rainbow-mode
     )
   "List of all packages to install and/or initialize. Built-in packages
 which require an initialization must be listed explicitly in the list.")
 
+(when colors-enable-rainbow-identifiers
+  (push 'rainbow-identifiers colors-packages))
+
 (defun colors/init-rainbow-blocks ()
   (use-package rainbow-blocks
     :disabled t