Add profile support

Closes #231

src/Spectre.Console/IProfileEnricher.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+
+namespace Spectre.Console
+{
+    /// <summary>
+    /// Represents something that can enrich a profile.
+    /// </summary>
+    public interface IProfileEnricher
+    {
+        /// <summary>
+        /// Gets whether or not this enricher is enabled.
+        /// </summary>
+        /// <param name="environmentVariables">The environment variables.</param>
+        /// <returns>Whether or not this enricher is enabled.</returns>
+        bool Enabled(IDictionary<string, string> environmentVariables);
+
+        /// <summary>
+        /// Enriches the profile.
+        /// </summary>
+        /// <param name="profile">The profile to enrich.</param>
+        void Enrich(Profile profile);
+    }
+}