Adds Argon2 for password protection (#123)

Projects/Argon2/Argon2Type.cs

@@ -0,0 +1,18 @@
+namespace Server.Accounting.Security
+{
+  /// <summary>
+  /// The type of Argon2 hashing algorithm to use.
+  /// </summary>
+  public enum Argon2Type
+  {
+    /// <summary>
+    /// The memory access is dependent upon the hash value (vulnerable to side-channel attacks)
+    /// </summary>
+    Argon2d = 0,
+
+    /// <summary>
+    /// The memory access is independent upon the hash value (safe from side-channel atacks)
+    /// </summary>
+    Argon2i = 1
+  }
+}