Add make diff to check integrity of home directory.

Makefile

@@ -3,9 +3,16 @@ prefix=~
 dotfiles:
 
 install: dotfiles
-	install -m 0644 tcshrc $(prefix)/.tcshrc
-	install -m 0644 bash_profile $(prefix)/.bash_profile
-	install -m 0644 bashrc $(prefix)/.bashrc
-	install -m 0644 zshenv $(prefix)/.zshenv
+	install -m 0644 dot.tcshrc $(prefix)/.tcshrc
+	install -m 0644 dot.bash_profile $(prefix)/.bash_profile
+	install -m 0644 dot.bashrc $(prefix)/.bashrc
+	install -m 0644 dot.zshenv $(prefix)/.zshenv
 	mkdir -p $(prefix)/.config/fish
-	install -m 0644 config/fish/config.fish $(prefix)/.config/fish/config.fish
+	install -m 0644 dot.config/fish/config.fish $(prefix)/.config/fish/config.fish
+
+diff:
+	diff dot.tcshrc $(prefix)/.tcshrc 2>/dev/null
+	diff dot.bash_profile $(prefix)/.bash_profile 2>/dev/null
+	diff dot.bashrc $(prefix)/.bashrc 2>/dev/null
+	diff dot.zshenv $(prefix)/.zshenv 2>/dev/null
+	diff dot.config/fish/config.fish $(prefix)/.config/fish/config.fish 2>/dev/null