Unix Compilation
----------------

To install, you need Tcl/Tk version 8.3 and ocaml version 3.04.  Getting
these is pretty straightforward on a unix box, so I'll just point you to the
URLs:

   http://www.scriptics.com    (for Tcl/Tk)
   http://www.ocaml.org

In order to compile planets, you simply move to the planets directory and
type:

   make planets

That should compile the planets executable.  Note that planets looks for and
saves universe files in the directory from which planets was invoked.

Win32 Compilation
-----------------

To compile under windows, you need to find and install a number of unix-style
tools.   The following explanation assumes a basic understanding of how to
get around in a unix shell.

Planets on Win32 currently depends on cygwin, a free (as in speech)
UNIX-compatibility layer.  Cygwin is available at http://cygwin.com.
Download the setup.exe file, run it, and follow the instructions.  You
should end up with a bash shell, gcc, and make, which are the main
prerequisites.

You also need to install Tcl/Tk 8.3.  You can get the ActiveTcl distribution
at http://scriptics.com or http://activestate.com.  Make sure you install
Tcl at a path that doesn't include any spaces.  Thus, installing at C:\Tcl
is OK, C:\Program Files\Tcl isn't.  

Once you have cygwin and Tcl/Tk installed, you should get ocaml 3.04.
Download that from www.ocaml.org.  Once you unpack the archive, read the
INSTALL file, which will give you the basic instructions.  You need to enable
labltk support, so your invocation of configure should look something like
this:

./configure -tklibs -L/cygdrive/C/Tcl/lib -tkdefs -I/cygdrive/C/Tcl/include

Look at the output of configure, and make sure that labltk was properly
configured.  You'll need to do "make world; make opt; make install" to
actually compile and install ocaml.

Once ocaml is installed, go to the planets directory.  Type "make clean; make
dep; make planets", and that, ideally, should do it.

At this point, planets should be invokeable from the cygwin shell.  To make
it work from the GUI, you need to ensure that cygwin1.dll is in the path.
You can do this either by copying cygwin1.dll from /usr/bin/ to the directory
planets is in, or else by editing the normal windows path to ensure 

