Move source files to where SPM expectes them to be

Sources/Stencil/DynamicMemberLookup.swift

@@ -0,0 +1,18 @@
+/// Marker protocol so we can know which types support `@dynamicMemberLookup`. Add this to your own types that support
+/// lookup by String.
+public protocol DynamicMemberLookup {
+  /// Get a value for a given `String` key
+  subscript(dynamicMember member: String) -> Any? { get }
+}
+
+public extension DynamicMemberLookup where Self: RawRepresentable {
+  /// Get a value for a given `String` key
+  subscript(dynamicMember member: String) -> Any? {
+    switch member {
+    case "rawValue":
+      return rawValue
+    default:
+      return nil
+    }
+  }
+}