fix: string parse and update sample

DragonLisp.l

@@ -35,7 +35,7 @@ int		[+-]?(0[xX][0-9A-Fa-f]*|0[0-7]*|[1-9][0-9]*)
 id		[a-zA-Z_][a-zA-Z_0-9]*
 blank	[ \t\v\r]
 comment	;[^\n\r]*
-string	\"[^\r\n]*\"
+string	\"(?:[^\"\\]|\\.)*\"
 
 and		[aA][nN][dD]
 or		[oO][rR]

sample.lisp

@@ -44,7 +44,8 @@
 
 (print (+ 1 2 3 4 5)) ; prints 15
 
-(print "Hello, world!") ; prints Hello, world!
+(print "Hello,
+ wo\n\"r\"ld!") ; prints Hello,(newline here) wo\n\"r\"ld!
 
 (defvar lower_bound 1)
 (loop