Refactor page content generators

CHDataManagement/Generator/Markdown/MarkdownProcessor.swift

@@ -0,0 +1,10 @@
+import Ink
+
+protocol MarkdownProcessor {
+
+    static var modifier: Modifier.Target { get }
+
+    init(content: Content, results: PageGenerationResults, language: ContentLanguage)
+
+    func process(html: String, markdown: Substring) -> String
+}