Partly fix white-space irregularities in lexer rules

chapters/syntax.tex

@@ -21,14 +21,15 @@ \section{Lexical conventions}\label{lexical-conventions}
 Q-CHAR = NONDIGIT | DIGIT | "!" | "#" | "$" | "%" | "&" | "(" | ")"
    | "*" | "+" | "," | "-" | "." | "/" | ":" | ";" | "<" | ">" | "="
    | "?" | "@" | "[" | "]" | "^" | "{" | "}" | "|" | "~" | " " | """
-S-ESCAPE = "\'" | "\"" | "\?" | "\\" |
-         "\a" | "\b" | "\f" | "\n" | "\r" | "\t" | "\v"
+S-ESCAPE = "\'" | "\"" | "\?" | "\\"
+   | "\a" | "\b" | "\f" | "\n" | "\r" | "\t" | "\v"
 DIGIT = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
 UNSIGNED-INTEGER = DIGIT { DIGIT }
-UNSIGNED-REAL = UNSIGNED-INTEGER  "." [ UNSIGNED-INTEGER ]
-   |  UNSIGNED_INTEGER [ "." [ UNSIGNED_INTEGER ] ]
-        ( "e" | "E" ) [ "+" | "-" ] UNSIGNED-INTEGER
-   |   "."  UNSIGNED-INTEGER [ ( "e" | "E" ) [ "+" | "-" ] UNSIGNED-INTEGER ]
+UNSIGNED-REAL =
+   UNSIGNED-INTEGER  "." [ UNSIGNED-INTEGER ]
+   | UNSIGNED_INTEGER [ "." [ UNSIGNED_INTEGER ] ]
+     ( "e" | "E" ) [ "+" | "-" ] UNSIGNED-INTEGER
+   | "."  UNSIGNED-INTEGER [ ( "e" | "E" ) [ "+" | "-" ] UNSIGNED-INTEGER ]
 \end{lstlisting}
 \textrm{S-CHAR} is any member of the Unicode character set
 (\url{http://www.unicode.org}; see \cref{mapping-package-class-structures-to-a-hierarchical-file-system} for storing as UTF-8 on files) except double-quote `"', and backslash `\textbackslash{}'.