Add a few new actions for commands and for variables

The default configuration now has new action keymaps for commands and
for variables, which have the symbol action map as their parent. For
commands, we have M-x, global-set-key and local-set-key actions. For
variables, we have set-variable, customize-set-variable and
customize-variable actions. (The last one creates a Customize buffer,
while the one before last uses the minibuffer.) Also, the binding for
Info-goto-emacs-command-node has been moved to the command map.

embark.el

@@ -121,11 +121,11 @@
     (environment-variables . embark-file-map) ; they come up in file completion
     (url . embark-url-map)
     (buffer . embark-buffer-map)
-    (command . embark-symbol-map)
-    (unicode-name . embark-unicode-name-map)
     (symbol . embark-symbol-map)
-    (variable . embark-symbol-map)
-    (minor-mode . embark-symbol-map)
+    (command . embark-command-map)
+    (variable . embark-variable-map)
+    (minor-mode . embark-command-map)
+    (unicode-name . embark-unicode-name-map)
     (package . embark-package-map)
     (bookmark . embark-bookmark-map)
     (region . embark-region-map)
@@ -1634,6 +1634,13 @@ This is whatever command opened the minibuffer in the first place."
   (setq this-command embark--command)   ; so the proper hooks apply
   (call-interactively embark--command))
 
+
+(defalias 'embark-execute-command
+  ;; this one is kind of embarrassing: embark-keymap-prompter gives
+  ;; execute-extended-command special treatment, so we need a command
+  ;; just like it... but with a different name!
+  #'execute-extended-command)
+
 (defun embark-insert (string)
   "Insert STRING at point."
   (interactive "sInsert: ")
@@ -1848,12 +1855,26 @@ and leaves the point to the left of it."
 (embark-define-keymap embark-symbol-map
   "Keymap for Embark symbol actions."
   ("h" describe-symbol)
-  ("c" Info-goto-emacs-command-node)
   ("s" embark-info-lookup-symbol)
   ("d" embark-find-definition)
   ("b" where-is)
   ("e" eval-expression))
 
+(embark-define-keymap embark-command-map
+  "Keymap for Embark command actions."
+  :parent embark-symbol-map
+  ("x" embark-execute-command)
+  ("c" Info-goto-emacs-command-node)
+  ("g" global-set-key)
+  ("l" local-set-key))
+
+(embark-define-keymap embark-variable-map
+  "Keymap for Embark variable actions."
+  :parent embark-symbol-map
+  ("=" set-variable)
+  ("c" customize-set-variable)
+  ("C" customize-variable))
+
 (embark-define-keymap embark-package-map
   "Keymap for Embark package actions."
   ("h" describe-package)