Introduce IndentLine action

Closes #1476

internal/action/actions.go

@@ -566,6 +566,20 @@ func (h *BufPane) IndentSelection() bool {
 	return false
 }
 
+// IndentLine moves the current line forward one indentation
+func (h *BufPane) IndentLine() bool {
+	if h.Cursor.HasSelection() {
+		return false
+	}
+
+	tabsize := int(h.Buf.Settings["tabsize"].(float64))
+	indentstr := h.Buf.IndentString(tabsize)
+	h.Buf.Insert(buffer.Loc{X: 0, Y: h.Cursor.Y}, indentstr)
+	h.Buf.RelocateCursors()
+	h.Relocate()
+	return true
+}
+
 // OutdentLine moves the current line back one indentation
 func (h *BufPane) OutdentLine() bool {
 	if h.Cursor.HasSelection() {

internal/action/bufpane.go

@@ -559,6 +559,7 @@ var BufKeyActions = map[string]BufKeyAction{
 	"Autocomplete":           (*BufPane).Autocomplete,
 	"CycleAutocompleteBack":  (*BufPane).CycleAutocompleteBack,
 	"OutdentLine":            (*BufPane).OutdentLine,
+	"IndentLine":             (*BufPane).IndentLine,
 	"Paste":                  (*BufPane).Paste,
 	"PastePrimary":           (*BufPane).PastePrimary,
 	"SelectAll":              (*BufPane).SelectAll,
@@ -664,6 +665,7 @@ var MultiActions = map[string]bool{
 	"IndentSelection":     true,
 	"OutdentSelection":    true,
 	"OutdentLine":         true,
+	"IndentLine":          true,
 	"Paste":               true,
 	"PastePrimary":        true,
 	"SelectPageUp":        true,