utf-16 macros (#13)

* macros

* typo (Aurorans Solis)

* handle malformed input better.

Author: Lokathor

book_src/SUMMARY.md

@@ -4,3 +4,5 @@
 * [Opening A Window](opening_a_window/index.md)
   * [Win32](opening_a_window/win32.md)
   * [Win32 Cleanup](opening_a_window/win32_cleanup.md)
+* [Appendix](appendix/index.md)
+  * [UTF-16 Literals](appendix/utf16_literals.md)

book_src/appendix/index.md

@@ -0,0 +1,7 @@
+
+# Appendix
+
+This part of the book has articles on stuff that's even more of a
+[yak shave](https://en.wiktionary.org/wiki/yak_shaving) than normal.
+
+It's useful, but it's just a diversion from our main focus.