Add install and clean commands to Makefile

Install to /usr/local/bin by default and prepare Makefile for
linking several different source files.

src/Makefile

@@ -1,2 +1,12 @@
-baps1: main.c
+CC		= cc -Wall -Wextra
-	$(CC) -Wall -Wextra -lm main.c -o baps1
+INST_PATH	= /usr/local/bin
+
+baps1: main.o
+	$(CC) -o baps1 main.o -lm
+
+main.o: main.c
+	$(CC) -c main.c
+install:
+	cp baps1 $(INST_PATH)/baps1
+clean:
+	rm baps1 *.o