🐧 Add keybindings for select-to-top/bottom

ctrl-shift-home/end are now mapped

Closes #2251

keymaps/linux.cson

@@ -69,6 +69,8 @@
   'ctrl-delete': 'editor:delete-to-end-of-word'
   'ctrl-home': 'core:move-to-top'
   'ctrl-end': 'core:move-to-bottom'
+  'cmd-shift-home': 'core:select-to-top'
+  'cmd-shift-end': 'core:select-to-bottom'
 
   # Sublime Parity
   'ctrl-a': 'core:select-all'