Add Makefile for easier install/uninstall

It will be useful for distributions and users :P.

I checked if this Makefile works not only on GNUj. So I checked bmake (NetBSD), busybox (userland) and various shells (zsh, bash, dash and ksh), so guess what? It "werks" (it took me a "while"). I hate GNUj more day by day, but OpenBSD doesn't work on my hardware :p.