force no-tab/trailing spaces with git hook

Remove unneeded stuff from pre-commit script

The check against an empty commit was not needed (it is only a security for the 1st commit after git init).
It could also possibly pose problems because of the redirection to /dev/null on some windows systems.

newline at EOF & fixed indent

.gitconfig

@@ -0,0 +1,2 @@
+[core]
+    whitespace = blank-at-eol,trailing-space,tab-in-indent