Deal w/ multi-line String Literals.

src/main/jflex/chocopy/pa1/ChocoPy.jflex

@@ -184,6 +184,7 @@ Comments = #[^\r\n]*
 }
 <STR>{
     {StringLiteral}           {currString+=yytext();}
+    \\$                       { /*'\' at the end of line, do nothing.*/ }
     "\""                      {yybegin(AFTER); return symbol(ChocoPyTokens.STRING, currString);}
 }
 <<EOF>>                       { return symbol(ChocoPyTokens.EOF); }