Add command to select text using page up/down keys

keymaps/darwin.cson

@@ -53,6 +53,8 @@
   'shift-down': 'core:select-down'
   'shift-left': 'core:select-left'
   'shift-right': 'core:select-right'
+  'shift-pageup': 'core:select-page-up'
+  'shift-pagedown': 'core:select-page-down'
   'delete': 'core:delete'
   'shift-delete': 'core:delete'
   'pageup': 'core:page-up'

keymaps/linux.cson

@@ -35,6 +35,8 @@
   'shift-down': 'core:select-down'
   'shift-left': 'core:select-left'
   'shift-right': 'core:select-right'
+  'shift-pageup': 'core:select-page-up'
+  'shift-pagedown': 'core:select-page-down'
   'delete': 'core:delete'
   'shift-delete': 'core:delete'
   'pageup': 'core:page-up'

keymaps/win32.cson

@@ -37,6 +37,8 @@
   'shift-down': 'core:select-down'
   'shift-left': 'core:select-left'
   'shift-right': 'core:select-right'
+  'shift-pageup': 'core:select-page-up'
+  'shift-pagedown': 'core:select-page-down'
   'delete': 'core:delete'
   'shift-delete': 'core:delete'
   'pageup': 'core:page-up'