Add a simple "build" script for people unfamiliar with bootstrap etc.

Makefile.am

@@ -2,6 +2,6 @@
 SUBDIRS = src tools art gfx
 DIST_SUBDIRS = $(SUBDIRS) maps
 
-EXTRA_DIST = bootstrap
+EXTRA_DIST = bootstrap build
 AUTOMAKE_OPTIONS = dist-bzip2
 

build

@@ -0,0 +1,9 @@
+#!/bin/sh
+
+set -ex
+
+./bootstrap
+./configure
+make clean
+make
+