Map ctrl-pageup/down to pane:show-next/previous-item

Closes #2724

keymaps/darwin.cson

@@ -69,6 +69,8 @@
   'cmd-}': 'pane:show-next-item'
   'cmd-alt-left': 'pane:show-previous-item'
   'cmd-alt-right': 'pane:show-next-item'
+  'ctrl-pageup': 'pane:show-previous-item'
+  'ctrl-pagedown': 'pane:show-next-item'
   'ctrl-tab': 'pane:show-next-item'
   'ctrl-shift-tab': 'pane:show-previous-item'
   'cmd-=': 'window:increase-font-size'

keymaps/linux.cson

@@ -45,6 +45,8 @@
   'shift-backspace': 'core:backspace'
   'ctrl-tab': 'pane:show-next-item'
   'ctrl-shift-tab': 'pane:show-previous-item'
+  'ctrl-pageup': 'pane:show-previous-item'
+  'ctrl-pagedown': 'pane:show-next-item'
   'ctrl-shift-up': 'core:move-up'
   'ctrl-shift-down': 'core:move-down'
   'ctrl-=': 'window:increase-font-size'

keymaps/win32.cson

@@ -47,6 +47,8 @@
   'shift-backspace': 'core:backspace'
   'ctrl-tab': 'pane:show-next-item'
   'ctrl-shift-tab': 'pane:show-previous-item'
+  'ctrl-pageup': 'pane:show-previous-item'
+  'ctrl-pagedown': 'pane:show-next-item'
   'ctrl-shift-up': 'core:move-up'
   'ctrl-shift-down': 'core:move-down'
   'ctrl-alt-up': 'editor:add-selection-above'