refactored ast, started lexer

include/lexer/TokenKind.h

@@ -0,0 +1,13 @@
+#pragma once
+
+namespace lexer {
+    enum class TokenKind {
+        Text,        // text
+        NewLine,     // new line
+        EOFile,      // end of file
+
+        HeaderMark,  // header mark ("#")
+        ListMark,    // list mark 
+        CodeFence    // code fence
+    };
+}