DuplicateLine: move selection duplication to separate Duplicate action

- Add a new Duplicate action which just duplicates the selection (and
  returns false if there is no selection).
- Change the behavior of the DuplicateLine action to only duplicate the
  current line, not the selection.
- Change the default action bound to Ctrl-d from DuplicateLine to
  Duplicate|DuplicateLine, so that the default behavior doesn't change.

This allows the user to rebind keybindings in a more flexible way, i.e.
to choose whether a key should duplicate just lines, or just selections,
or both, - in a similar fashion to Copy, Cut, Delete actions.

internal/action/actions.go

@@ -1268,19 +1268,22 @@ func (h *BufPane) CutLine() bool {
 	return true
 }
 
-// DuplicateLine duplicates the current line or selection
-func (h *BufPane) DuplicateLine() bool {
-	var infoMessage = "Duplicated line"
-	if h.Cursor.HasSelection() {
-		infoMessage = "Duplicated selection"
-		h.Buf.Insert(h.Cursor.CurSelection[1], string(h.Cursor.GetSelection()))
-	} else {
-		h.Cursor.End()
-		h.Buf.Insert(h.Cursor.Loc, "\n"+string(h.Buf.LineBytes(h.Cursor.Y)))
-		// h.Cursor.Right()
+// Duplicate the selection
+func (h *BufPane) Duplicate() bool {
+	if !h.Cursor.HasSelection() {
+		return false
 	}
+	h.Buf.Insert(h.Cursor.CurSelection[1], string(h.Cursor.GetSelection()))
+	InfoBar.Message("Duplicated selection")
+	h.Relocate()
+	return true
+}
 
-	InfoBar.Message(infoMessage)
+// DuplicateLine duplicates the current line
+func (h *BufPane) DuplicateLine() bool {
+	h.Cursor.End()
+	h.Buf.Insert(h.Cursor.Loc, "\n"+string(h.Buf.LineBytes(h.Cursor.Y)))
+	InfoBar.Message("Duplicated line")
 	h.Relocate()
 	return true
 }

internal/action/bufpane.go

@@ -784,6 +784,7 @@ var BufKeyActions = map[string]BufKeyAction{
 	"CopyLine":                  (*BufPane).CopyLine,
 	"Cut":                       (*BufPane).Cut,
 	"CutLine":                   (*BufPane).CutLine,
+	"Duplicate":                 (*BufPane).Duplicate,
 	"DuplicateLine":             (*BufPane).DuplicateLine,
 	"DeleteLine":                (*BufPane).DeleteLine,
 	"MoveLinesUp":               (*BufPane).MoveLinesUp,
@@ -910,6 +911,7 @@ var MultiActions = map[string]bool{
 	"Copy":                      true,
 	"Cut":                       true,
 	"CutLine":                   true,
+	"Duplicate":                 true,
 	"DuplicateLine":             true,
 	"DeleteLine":                true,
 	"MoveLinesUp":               true,

internal/action/defaults_darwin.go

@@ -48,7 +48,7 @@ var bufdefaults = map[string]string{
 	"Ctrl-c":         "Copy|CopyLine",
 	"Ctrl-x":         "Cut|CutLine",
 	"Ctrl-k":         "CutLine",
-	"Ctrl-d":         "DuplicateLine",
+	"Ctrl-d":         "Duplicate|DuplicateLine",
 	"Ctrl-v":         "Paste",
 	"Ctrl-a":         "SelectAll",
 	"Ctrl-t":         "AddTab",

internal/action/defaults_other.go

@@ -51,7 +51,7 @@ var bufdefaults = map[string]string{
 	"Ctrl-c":         "Copy|CopyLine",
 	"Ctrl-x":         "Cut|CutLine",
 	"Ctrl-k":         "CutLine",
-	"Ctrl-d":         "DuplicateLine",
+	"Ctrl-d":         "Duplicate|DuplicateLine",
 	"Ctrl-v":         "Paste",
 	"Ctrl-a":         "SelectAll",
 	"Ctrl-t":         "AddTab",

runtime/help/keybindings.md

@@ -494,7 +494,7 @@ conventions for text editing defaults.
     "Ctrl-c":         "Copy|CopyLine",
     "Ctrl-x":         "Cut|CutLine",
     "Ctrl-k":         "CutLine",
-    "Ctrl-d":         "DuplicateLine",
+    "Ctrl-d":         "Duplicate|DuplicateLine",
     "Ctrl-v":         "Paste",
     "Ctrl-a":         "SelectAll",
     "Ctrl-t":         "AddTab",