Say 'escape sequence', not 'escape code'

Although both terms seems to be in use, 'escape sequence' seems to be the more generally recognized one.

chapters/lexicalstructure.tex

@@ -173,7 +173,10 @@ \subsection{Boolean Literals}\label{boolean-literals}
 
 \subsection{Strings}\label{strings}
 
-String literals appear between double quotes as in \lstinline!"between"!.  Any character in the Modelica language character set (see \cref{lexical-conventions} for allowed characters) apart from double quote (\lstinline!"!) and backslash (\lstinline!\!), including new-line, can be \emph{directly} included in a string without using an escape code.  Certain characters in string literals can be represented using escape codes, i.e., the character is preceded by a backslash (\lstinline!\!) within the string. Those characters are:
+String literals appear between double quotes as in \lstinline!"between"!.
+Any character in the Modelica language character set (see \cref{lexical-conventions} for allowed characters) apart from double quote (\lstinline!"!) and backslash (\lstinline!\!), including new-line, can be \emph{directly} included in a string without using an escape sequence.
+Certain characters in string literals can be represented using escape sequences, i.e., the character is preceded by a backslash (\lstinline!\!) within the string.
+Those characters are:
 \begin{center}
 \begin{tabular}{c l}
 \hline