add N marker for displaying full track info and make n show only a number

generated filename was ugly if track tag was in format
xx/xx, so %n should display only current track number.

doc/config

@@ -70,7 +70,8 @@
 ## %t - title
 ## %b - album
 ## %y - year
-## %n - track number
+## %n - track number (01/12 -> 01)
+## %N - full track info (01/12 -> 01/12)
 ## %g - genre
 ## %c - composer
 ## %p - performer

doc/ncmpcpp.1

@@ -295,7 +295,8 @@ For song format you can use:
  %t - title
  %b - album
  %y - year
- %n - track number
+ %n - track number (01/12 -> 01)
+ %N - full track info (01/12 -> 01/12)
  %g - genre
  %c - composer
  %p - performer

src/display.cpp

@@ -65,6 +65,7 @@ std::string Display::Columns()
 				tag = "Year";
 				break;
 			case 'n':
+			case 'N':
 				tag = "Track";
 				break;
 			case 'g':
@@ -149,6 +150,9 @@ void Display::SongsInColumns(const MPD::Song &s, void *, Menu<MPD::Song> *menu)
 				get = &MPD::Song::GetDate;
 				break;
 			case 'n':
+				get = &MPD::Song::GetTrackNumber;
+				break;
+			case 'N':
 				get = &MPD::Song::GetTrack;
 				break;
 			case 'g':

src/song.cpp

@@ -163,6 +163,20 @@ std::string MPD::Song::GetTrack() const
 		return itsSong->track;
 }
 
+std::string MPD::Song::GetTrackNumber() const
+{
+	if (!itsSong->track)
+		return "";
+	const char *slash = strrchr(itsSong->track, '/');
+	if (slash)
+	{
+		std::string result(itsSong->track, slash-itsSong->track);
+		return result[0] != '0' && result.length() == 1 ? "0"+result : result;
+	}
+	else
+		return GetTrack();
+}
+
 std::string MPD::Song::GetDate() const
 {
 	return !itsSong->date ? "" : itsSong->date;
@@ -332,6 +346,9 @@ std::string MPD::Song::ParseFormat(std::string::const_iterator &it) const
 					get = &MPD::Song::GetDate;
 					break;
 				case 'n':
+					get = &MPD::Song::GetTrackNumber;
+					break;
+				case 'N':
 					get = &MPD::Song::GetTrack;
 					break;
 				case 'g':

src/song.h

@@ -46,6 +46,7 @@ namespace MPD
 			std::string GetTitle() const;
 			std::string GetAlbum() const;
 			std::string GetTrack() const;
+			std::string GetTrackNumber() const;
 			std::string GetDate() const;
 			std::string GetGenre() const;
 			std::string GetComposer() const;