Add/Fix: org-ql-view-mode, and check when refreshing

Use a derived major mode for org-ql-view buffers, and ensure that mode
is active when calling org-ql-view-refresh, to avoid interfering with
buffers in other modes if the user calls the command by accident.

See
<b87156f2bb>.
Thanks to Alois Janíček (@AloisJanicek) for discovering the bug.

Released as 0.4.3.

org-ql-view.el

@@ -309,6 +309,8 @@ TYPE may be `ts', `ts-active', `ts-inactive', `clocked', or
 If PROMPT is non-nil (interactively, with prefix), prompt to
 update search arguments."
   (interactive "P")
+  (unless (eq major-mode 'org-ql-view-mode)
+    (user-error "Not an Org QL View buffer"))
   (let* ((current-line (buffer-substring-no-properties (line-beginning-position) (line-end-position)))
          (old-pos (point))
          (defaults (list org-ql-view-buffers-files
@@ -354,6 +356,10 @@ update search arguments."
 
 ;;;; Functions
 
+(define-derived-mode org-ql-view-mode org-agenda-mode "Org QL View"
+  "Major mode for `org-ql-view' buffers."
+  (setf buffer-read-only t))
+
 (defun org-ql-view--list-buffer ()
   "Return view list buffer."
   (with-current-buffer (get-buffer-create "*Org QL View List*")
@@ -468,9 +474,8 @@ with human-readable strings."
 If NAME is non-nil, return buffer by that name instead of using
 default buffer."
   (with-current-buffer (get-buffer-create (or name (concat org-ql-view-buffer-name-prefix "*")))
-    (unless (eq major-mode 'org-agenda-mode)
-      (org-agenda-mode)
-      (setf buffer-read-only t))
+    (unless (eq major-mode 'org-ql-view-mode)
+      (org-ql-view-mode))
     (current-buffer)))
 
 (defun org-ql-view--format-relative-date (difference)