Added IGeographicLocation message

src/NmeaParser/Nmea/Gga.cs

@@ -26,7 +26,7 @@ namespace NmeaParser.Messages
     /// </remarks>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Gpgga")]
     [NmeaMessageType("--GGA")]
-    public class Gga : NmeaMessage, ITimestampedMessage
+    public class Gga : NmeaMessage, ITimestampedMessage, IGeographicLocation
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Gga"/> class.

src/NmeaParser/Nmea/Gll.cs

@@ -24,7 +24,7 @@ namespace NmeaParser.Messages
     /// </remarks>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Gll")]
     [NmeaMessageType("--GLL")]
-    public class Gll : NmeaMessage, ITimestampedMessage
+    public class Gll : NmeaMessage, ITimestampedMessage, IGeographicLocation
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Gll"/> class.

src/NmeaParser/Nmea/Gns.cs

@@ -38,7 +38,7 @@ namespace NmeaParser.Messages
     /// </remarks>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Gns")]
     [NmeaMessageType("--GNS")]
-    public class Gns : NmeaMessage, ITimestampedMessage
+    public class Gns : NmeaMessage, ITimestampedMessage, IGeographicLocation
     {
         /*
          * Example of GNS messages:

src/NmeaParser/Nmea/IGeographicLocation.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NmeaParser.Messages
+{
+    /// <summary>
+    /// Indicates a message that contains a latitude and longitude value
+    /// </summary>
+    public interface IGeographicLocation
+    {
+        /// <summary>
+        /// Gets the latitude component of the location
+        /// </summary>
+        double Latitude { get; }
+
+        /// <summary>
+        /// Gets the longitude component of the location
+        /// </summary>
+        double Longitude { get; }
+    }
+}

src/NmeaParser/Nmea/Rma.cs

@@ -26,7 +26,7 @@ namespace NmeaParser.Messages
     /// </remarks>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Gprmb")]
     [NmeaMessageType("--RMA")]
-    public class Rma : NmeaMessage
+    public class Rma : NmeaMessage, IGeographicLocation
     {
         /// <summary>
         /// Positioning system status field

src/NmeaParser/Nmea/Rmc.cs

@@ -28,7 +28,7 @@ namespace NmeaParser.Messages
     /// </remarks>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Gprmc")]
     [NmeaMessageType("--RMC")]
-    public class Rmc : NmeaMessage, ITimestampedMessage
+    public class Rmc : NmeaMessage, ITimestampedMessage, IGeographicLocation
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="Rmc"/> class.