Fixed ConvertFrom for orient and aspect ratio

Source/DataTypes/SvgAspectRatioConverter.cs

@@ -87,11 +87,6 @@ namespace Svg.DataTypes
 
 		public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
 		{
-			if (destinationType == typeof(string))
-			{
-				return ((SvgUnit)value).ToString();
-			}
-
 			return base.ConvertTo(context, culture, value, destinationType);
 		}
 	}

Source/DataTypes/SvgOrientConverter.cs

@@ -52,11 +52,6 @@ namespace Svg.DataTypes
 
 		public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
 		{
-			if (destinationType == typeof(string))
-			{
-				return ((SvgUnit)value).ToString();
-			}
-
 			return base.ConvertTo(context, culture, value, destinationType);
 		}
 	}