Magic file readme

To make the executables installation independent, the "DIE_MAGIC" 
setting is no longer compiled into the executable, but created at
run-time in the file .magic.dat.

If the program is compiled on an old installation (where .magic.h
already exists) this will be placed into the .magic.dat file in 
the installation directory.

(Note: if the executable files are installed into a DIFFERENT 
       place than where actually run, a .magic.dat file will
       be create where the judge runs.)

-Millis Miller 12th November 2000