adapt build instructions in README to the new build system

Author: fabian

README

@@ -71,24 +71,36 @@ distributions. Patches are always welcome. ;-)
 General Hints
 -------------
 
-To compile the source code under Linux, change to the rott/ directory and type:
+The following prerequisites are required to compile the source code:
 
-  make clean
-  make
+  autoconf
+  automake
+  pkg-config
+  SDL 1.2
+  SDL_mixer 1.2
+
+To compile the source code, type the following:
 
-The build system is setup to use shareware binaries.  If you want to use one
-of the commercial versions of ROTT, compile with:
+  autoreconf -fiv
+  ./configure
+  make
 
-  make SHAREWARE=0
+The resulting binaries can be found in the rott/ directory.
 
+The build system is setup to build the commercial variant of ROTT.
 This variant supports the Registered Version, the "Super ROTT" CD Version and
 the "Site License" CD Version of the game by automatically detecting and
 loading their corresponding multiplayer map files.
 
-You may want to edit rott/Makefile to make your changes persistent.
+If you want to build the shareware version of ROTT, configure with:
+
+  ./configure --enable-shareware
 
-It is generally recommended to build against the most recent version of 
-the Simple Direct Media Layer and SDL_mixer.
+Additionally, you may pass the "--enable-suffix=<suffix>" parameter to
+./configure in order to append a suffix to the executable file name,
+e.g. to tell the commercial and the shareware variants apart. You may
+also want to pass the "--enable-datadir=<datadir>" parameter to point
+the executables to the location of your game data files.
 
 
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