Fix backslash escapes not being properly handled

Closes #134

Author: mavolin

Makefile

@@ -179,6 +179,9 @@ $(TEST_DIR)/issue_80/issue_80.go: $(TEST_DIR)/issue_80/issue_80.peg $(BINDIR)/pi
 $(TEST_DIR)/issue_115/issue_115.go: $(TEST_DIR)/issue_115/issue_115.peg $(BINDIR)/pigeon
 	$(BINDIR)/pigeon -nolint $< > $@
 
+$(TEST_DIR)/issue_134/issue_134.go: $(TEST_DIR)/issue_134/issue_134.peg $(BINDIR)/pigeon
+	$(BINDIR)/pigeon -nolint $< > $@
+
 $(TEST_DIR)/left_recursion/left_recursion.go: \
 		$(TEST_DIR)/left_recursion/standart/leftrecursion/left_recursion.go \
 		$(TEST_DIR)/left_recursion/optimized/leftrecursion/left_recursion.go \

grammar/pigeon.peg

@@ -324,9 +324,9 @@ CodeBlock ← '{' Code '}' {
 
 Code ← ( ( Comment / CodeStringLiteral / ![{}] SourceChar )+ / '{' Code '}' )*
 
-CodeStringLiteral ← '"' (`\"` / [^"\r\n])* '"' /
+CodeStringLiteral ← '"' (`\"` / `\\` / [^"\r\n])* '"' /
                     '`' [^`]* '`' /
-                    '\'' (`\'` / [^']+) '\''
+                    '\'' (`\'` / `\\` / [^']+) '\''
 
 __ ← ( Whitespace / EOL / Comment )*
 _ ← ( Whitespace / MultiLineCommentNoLineTerminator )*