Add Shift-Page Up/Down keybindings (zyedidia#3407)

* Add Shift-Page Up/Down keybindings in defaults_other.go

* Add Shift-Page Up/Down keybindings in defaults_darwin.go

* Document Shift-Page Up/Down keybindings in keybindings.md

* Fix indentation

Author: injust

internal/action/defaults_darwin.go

@@ -62,6 +62,8 @@ var bufdefaults = map[string]string{
 	"PageDown":       "CursorPageDown",
 	"CtrlPageUp":     "PreviousTab",
 	"CtrlPageDown":   "NextTab",
+	"ShiftPageUp":    "SelectPageUp",
+	"ShiftPageDown":  "SelectPageDown",
 	"Ctrl-g":         "ToggleHelp",
 	"Alt-g":          "ToggleKeyMenu",
 	"Ctrl-r":         "ToggleRuler",

internal/action/defaults_other.go

@@ -65,6 +65,8 @@ var bufdefaults = map[string]string{
 	"PageDown":       "CursorPageDown",
 	"CtrlPageUp":     "PreviousTab",
 	"CtrlPageDown":   "NextTab",
+	"ShiftPageUp":    "SelectPageUp",
+	"ShiftPageDown":  "SelectPageDown",
 	"Ctrl-g":         "ToggleHelp",
 	"Alt-g":          "ToggleKeyMenu",
 	"Ctrl-r":         "ToggleRuler",

runtime/help/keybindings.md

@@ -512,6 +512,8 @@ conventions for text editing defaults.
     "PageDown":       "CursorPageDown",
     "CtrlPageUp":     "PreviousTab",
     "CtrlPageDown":   "NextTab",
+    "ShiftPageUp":    "SelectPageUp",
+    "ShiftPageDown":  "SelectPageDown",
     "Ctrl-g":         "ToggleHelp",
     "Alt-g":          "ToggleKeyMenu",
     "Ctrl-r":         "ToggleRuler",