add altcoin support for althash / htmlcoin (#2485)

* Switch Althash, keypath, hitbtc ticker

* add Althash

* add Althash

* switch to coingecko provider

* add Althash logo

* Fix stacking issue with rate call

* bump NBitcoin to 5.0.77

* bump NBXplorer.Client to 3.0.21

BTCPayServer.Common/Altcoins/BTCPayNetworkProvider.Althash.cs

@@ -0,0 +1,29 @@
+using NBitcoin;
+using NBXplorer;
+
+namespace BTCPayServer
+{
+    public partial class BTCPayNetworkProvider
+    {
+        public void InitAlthash()
+        {
+            var nbxplorerNetwork = NBXplorerNetworkProvider.GetFromCryptoCode("HTML");
+            Add(new BTCPayNetwork()
+            {
+                CryptoCode = nbxplorerNetwork.CryptoCode,
+                DisplayName = "Althash",
+                BlockExplorerLink = NetworkType == ChainName.Mainnet ? "https://explorer.htmlcoin.com/api/tx/{0}" : "https://explorer.htmlcoin.com/api/tx/{0}",
+                NBXplorerNetwork = nbxplorerNetwork,
+                UriScheme = "htmlcoin",
+                DefaultRateRules = new[]
+                {
+                                "HTML_X = HTML_USD",
+                                "HTML_USD = hitbtc(HTML_USD)"
+                },
+                CryptoImagePath = "imlegacy/althash.png",
+                DefaultSettings = BTCPayDefaultSettings.GetDefaultSettings(NetworkType),
+                CoinType = NetworkType == ChainName.Mainnet ? new KeyPath("88'") : new KeyPath("1'")
+            });
+        }
+    }
+}

BTCPayServer.Common/BTCPayNetworkProvider.cs

@@ -51,6 +51,7 @@ namespace BTCPayServer
             InitMonacoin();
             InitDash();
             InitFeathercoin();
+            InitAlthash();
             InitGroestlcoin();
             InitViacoin();
             InitMonero();

BTCPayServer.Common/BTCPayServer.Common.csproj

@@ -4,9 +4,9 @@
 
   <ItemGroup>
     <FrameworkReference Include="Microsoft.AspNetCore.App" />
-    <PackageReference Include="NBXplorer.Client" Version="3.0.20" />
+    <PackageReference Include="NBXplorer.Client" Version="3.0.21" />
   </ItemGroup>
   <ItemGroup Condition="'$(Altcoins)' != 'true'">
     <Compile Remove="Altcoins\**\*.cs"></Compile>
   </ItemGroup>
-</Project>
+</Project>

BTCPayServer.Rating/Currencies.json

@@ -1266,6 +1266,13 @@
       "symbol":null,
       "crypto":true
    },
+   {
+      "name":"Althash",
+      "code":"HTML",
+      "divisibility":8,
+      "symbol":null,
+      "crypto":true
+   },
    {
       "name":"CHC",
       "code":"CHC",