Improve makefile, change dir structure

set1/Makefile

@@ -1,14 +1,19 @@
+CC      = gcc
+CFLAGS  = -Wall -Wpedantic -Wextra -std=c99
+DEBUG   = -g
+LINK    = 
+SRC_DIR = src
+OUT_DIR = bin
+TARGETS = base64
 
-CC = gcc
-CFLAGS = -Wall -Wpedantic -Wextra -std=c99 -g
-RM = rm
 
-all: base64
+all: $(TARGETS)
 
-base64: base64.c
-	$(CC) -o $@ $^
+%: $(SRC_DIR)/%.c
+	$(CC) $(CFLAGS) $(LINK) $< -o $(OUT_DIR)/$@
 
 clean:
-	$(RM) base64
-	$(RM) *.o
+	$(RM) *.o $(OUT_DIR)/*
+
+.PHONY: all clean