split scanner and parser

Makefile

@@ -1,6 +1,6 @@
 PHPFILE=example.php
 
-all: ./parser/php7.go ./parser/scanner.go
+all: ./parser/php7.go ./scanner/scanner.go
 	rm -f y.output
 	gofmt -l -s -w *.go
 	go build
@@ -11,7 +11,7 @@ run: all
 test: all
 	go test ./... --cover
 
-./parser/scanner.go: ./parser/scanner.l
+./scanner/scanner.go: ./scanner/scanner.l
 	golex -o $@ $<
 
 ./parser/php7.go: ./parser/php7.y