Tidied up code, removed obsolete getpass and implemented replacement

Makefile

@@ -1,12 +1,22 @@
-salty: salty.o
-	cc ./build/salty.o -o ./build/salty -lsodium -I.
-	rm ./build/salty.o
+CC = gcc
+CFLAGS = -Wall -Wextra -std=c99 -O2
+LDFLAGS = -lsodium
+BUILD_DIR = build
+PREFIX = /usr/local
 
-salty.o: build
-	cc -c salty.c -o ./build/salty.o -lsodium -I.
+all: $(BUILD_DIR)/salty
 
-build:
-	mkdir -p ./build
+$(BUILD_DIR)/salty: salty.c pawstd.h | $(BUILD_DIR)
+	$(CC) $(CFLAGS) -o $@ salty.c $(LDFLAGS)
+
+$(BUILD_DIR):
+	mkdir -p $(BUILD_DIR)
+
+clean:
+	rm -rf $(BUILD_DIR)
 
 install:
-	install -m 755 ./build/salty /usr/local/bin/salty
+	install -m 755 $(BUILD_DIR)/salty /usr/local/bin/salty
+
+uninstall:
+	rm $(PREFIX)/bin/salty