added profiling target, makes it easier

Makefile

@@ -1,5 +1,8 @@
-.PHONY: all
-all:
+.PHONY all:
+all: build
+
+.PHONY: build
+build:
 	make -C src
 	mv src/golsky .
 
@@ -7,3 +10,8 @@ all:
 clean:
 	make -C src clean
 	rm -f dump* rect*
+
+.PHONY: profile
+profile: build
+	./golsky -W 1500 -H 1500 -d --profile-file cpu.profile
+	go tool pprof --http localhost:8888 golsky cpu.profile