libnjb: Frame types for different song ID frames

# Frame types for different song ID frames

## Defines
#define | NJB_TYPE_STRING 0x00
#define | NJB_TYPE_UINT16 0x02
#define | NJB_TYPE_UINT32 0x03

## Define Documentation

#define NJB_TYPE_STRING 0x00

A string type song ID frame

Examples:
  tracks.c.

Referenced by NJB_Replace_Track_Tag(), NJB_Songid_Frame_Destroy(), NJB_Songid_Frame_New_String(), songid_pack(), and songid_sanity_check().

#define NJB_TYPE_UINT16 0x02

An unsigned 16 bit integer type song ID frame

Examples:
  tracks.c.

Referenced by NJB_Replace_Track_Tag(), NJB_Songid_Frame_New_Uint16(), songid_pack(), and songid_sanity_check().

#define NJB_TYPE_UINT32 0x03

An unsigned 32 bit integer type song ID frame

Examples:
  tracks.c.

Referenced by NJB_Replace_Track_Tag(), NJB_Songid_Frame_New_Uint32(), songid_pack(), and songid_sanity_check().