app/email: flesh out evil support & add +email/mark-multiple for visual mode

modules/app/email/autoload.el

@@ -10,3 +10,18 @@
   (interactive)
   (call-interactively 'mu4e-compose-new))
 
+;;;###autoload
+(defun +email/mark-multiple (beg end)
+  "Mark all messages within the current selection in mu4e's header view. Uses
+`this-command-keys' to see what flag you mean."
+  (interactive "r")
+  (let ((command (lookup-key mu4e-headers-mode-map (this-command-keys)))
+        (lines (count-lines beg end)))
+    (unless command
+      (error "No valid command"))
+    (when (featurep 'evil)
+      (evil-normal-state))
+    (save-excursion
+      (goto-char beg)
+      (dotimes (_ lines)
+        (call-interactively command)))))