Add some comments/questions and one typo fix

book.tex

@@ -29,6 +29,10 @@
 % Computer Modern is already the default. -Jeremy
 %\renewcommand{\ttdefault}{cmtt}
 
+% Peanut gallery comments:
+\definecolor{comment-red}{rgb}{0.8,0,0}
+\newcommand{\rn}[1]{{\color{comment-red}{(RRN: #1)}}}
+
 \lstset{%
 language=Lisp,
 basicstyle=\ttfamily\small,
@@ -141,6 +145,9 @@ passes~\citep{Sarkar:2004fk,Keep:2012aa}. I took this compiler course
 in the early 2000's, as part of my Ph.D. studies at Indiana
 University. Needless to say, I enjoyed the course immensely.
 
+\rn{I think that 1999 when I took it was the first micropass semester, and that
+  that approach preceded the infrastructure work by Dipa.}
+
 One of my classmates, Abdulaziz Ghuloum, observed that the
 front-to-back organization of the course made it difficult for
 students to understand the rationale for the compiler
@@ -742,6 +749,9 @@ evaluator on several examples and tests the output program.  The
 (test-pe `(- (+ (read) (- 5))))
 \end{lstlisting}
 
+\rn{Do we like the explicit whitespace?  I've never been fond of it, in part
+  because it breaks copy/pasting.  But, then again, so do most of the quotes.}
+
 \begin{exercise}
 \normalfont % I don't like the italics for exercises. -Jeremy
 We challenge the reader to improve on the simple partial evaluator in
@@ -773,7 +783,7 @@ following grammar.
 
 This chapter concerns the challenge of compiling a subset of Racket,
 which we name $R_1$, to x86-64 assembly code~\citep{Intel:2015aa}.
-(Hence force we shall refer to x86-64 simply as x86).  The chapter
+(Henceforth we shall refer to x86-64 simply as x86).  The chapter
 begins with a description of the $R_1$ language (Section~\ref{sec:s0})
 and then a description of x86 (Section~\ref{sec:x86}). The
 x86 assembly language is quite large, so we only discuss what is