Add new key bindings

* move to the previous Org heading with C-c h
* open `calc` with C-t C-c

configuration.org

@@ -2479,7 +2479,8 @@ This is a big one; I use a lot of customisation here.
    ("SPC" . org-space-key)
    ("C-c l" . org-toggle-link-display)
    ("C-a" . gpolonkai/move-to-beginning-of-line)
-   ("C-e" . gpolonkai/move-to-end-of-line)))
+   ("C-e" . gpolonkai/move-to-end-of-line)
+   ("h" . outline-previous-heading)))
 #+END_SRC
 
 ** Org bullets
@@ -3032,7 +3033,8 @@ directory.  It is available from [[http://plantuml.com/download][here]].
  ("o i" . gpolonkai/visit-init-file)
  ("o o" . gpolonkai/visit-org-index)
  ("u" . browse-url-at-point)
- ("C" . clean-buffer-list))
+ ("C" . clean-buffer-list)
+ ("C-c" . calc))
 #+END_SRC
 
 ** TODO These fail to work using ~bind-keys~, but why?