Add ImageflowMiddlewareOptions.SetLicenseKey() and .SetMyOpenSourceProjectUrl()

Author: lilith

Diff for: src/Imageflow.Server/EnforceLicenseWith.cs

@@ -0,0 +1,8 @@
+namespace Imageflow.Server
+{
+    public enum EnforceLicenseWith
+    {
+        RedDotWatermark,
+        Http422Error
+    }
+}

Diff for: src/Imageflow.Server/ImageflowMiddlewareOptions.cs

@@ -12,6 +12,11 @@ public class ImageflowMiddlewareOptions
         public ImageflowMiddlewareOptions()
         {
         }
+        
+        internal string LicenseKey { get; set; } 
+        internal EnforceLicenseWith EnforcementMethod { get; set; }
+        
+        public string MyOpenSourceProjectUrl { get; set; }
 
         public bool AllowMemoryCaching { get; set; } = false;
 
@@ -80,6 +85,36 @@ public ImageflowMiddlewareOptions HandleExtensionlessRequestsUnder(string prefix
             ExtensionlessPaths.Add(new ExtensionlessPath() { Prefix = prefix, PrefixComparison = prefixComparison});
             return this;
         }
+
+        /// <summary>
+        /// Use this if you are complying with the AGPL v3 and open-sourcing your project.
+        /// Provide the URL to your version control system or source code download page.
+        /// Use .SetLicenseKey() instead if you are not open-sourcing your project.
+        /// </summary>
+        /// <param name="myOpenSourceProjectUrl">Provide the URL to your version control
+        /// system or source code download page.</param>
+        /// <returns></returns>
+        public ImageflowMiddlewareOptions SetMyOpenSourceProjectUrl(string myOpenSourceProjectUrl)
+        {
+            MyOpenSourceProjectUrl = myOpenSourceProjectUrl;
+            return this;
+        }
+        
+        /// <summary>
+        /// If you do not call this, Imageflow.Server will watermark image requests with a red dot. 
+        ///
+        /// If you are open-sourcing your project and complying with the AGPL v3, you can call
+        /// .SetMyOpenSourceProjectUrl() instead.
+        /// </summary>
+        /// <param name="licenseKey"></param>
+        /// <param name="enforcementMethod"></param>
+        /// <returns></returns>
+        public ImageflowMiddlewareOptions SetLicenseKey(EnforceLicenseWith enforcementMethod, string licenseKey)
+        {
+            EnforcementMethod = enforcementMethod;
+            LicenseKey = licenseKey;
+            return this;
+        }
 
         public ImageflowMiddlewareOptions SetRequestSignatureOptions(RequestSignatureOptions options)
         {