Make :pipe command more generic

widgets/msgviewer.go

@@ -227,7 +227,7 @@ func (mv *MessageViewer) ToggleHeaders() {
 	switcher.Invalidate()
 }
 
-func (mv *MessageViewer) CurrentPart() *PartInfo {
+func (mv *MessageViewer) SelectedMessagePart() *PartInfo {
 	switcher := mv.switcher
 	part := switcher.parts[switcher.selected]
 
@@ -332,13 +332,6 @@ type PartViewer struct {
 	term        *Terminal
 }
 
-type PartInfo struct {
-	Index []int
-	Msg   *types.MessageInfo
-	Part  *imap.BodyStructure
-	Store *lib.MessageStore
-}
-
 func NewPartViewer(conf *config.AercConfig,
 	store *lib.MessageStore, msg *types.MessageInfo,
 	part *imap.BodyStructure, showHeaders bool,