added constructors for PolylineEncoder

Author: petesramek

src/PolylineAlgorithm.Abstraction/PolylineEncoder.cs

@@ -18,10 +18,31 @@ namespace PolylineAlgorithm.Abstraction;
 /// Implements the <see cref="IPolylineEncoder{TCoordinate, TPolyline}"/> interface.
 /// </summary>
 public abstract class PolylineEncoder<TCoordinate, TPolyline> : IPolylineEncoder<TCoordinate, TPolyline> {
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PolylineEncoder{TCoordinate, TPolyline}"/> class
+    /// using the default <see cref="PolylineEncodingOptions{TCoordinate}"/>.
+    /// </summary>
+    public PolylineEncoder()
+        : this(new PolylineEncodingOptions<TCoordinate>()) { }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PolylineEncoder{TCoordinate, TPolyline}"/> class
+    /// with the specified <see cref="PolylineEncodingOptions{TCoordinate}"/>.
+    /// </summary>
+    /// <param name="options">
+    /// The <see cref="PolylineEncodingOptions{TCoordinate}"/> to use for encoding operations.
+    /// </param>
+    /// <exception cref="ArgumentNullException">
+    /// Thrown when <paramref name="options"/> is <see langword="null"/>.
+    /// </exception>
+    public PolylineEncoder(PolylineEncodingOptions<TCoordinate> options) {
+        Options = options ?? throw new ArgumentNullException(nameof(options));
+    }
+
     /// <summary>
     /// Gets the encoding options used by this polyline encoder.
     /// </summary>
-    public abstract PolylineEncodingOptions<TCoordinate> Options { get; }
+    public PolylineEncodingOptions<TCoordinate> Options { get; }
 
     /// <summary>
     /// Encodes a collection of <typeparamref name="TCoordinate"/> instances into an encoded <typeparamref name="TPolyline"/> string.