SYNOPSIS
    string find_savefile (object pl)
    string find_savefile (string pl)

DESCRIPTION
    Return the name of the savefile of player <pl>, but without the 
    trailing ".o".
    If <pl> is not valid, 0 is returned.

    Note that for wizards, <pl> may be any object carrying the euid of 
    that wizard.

EXAMPLE
    find_savefile(find_player("mateese")) --> "/save/m/mateese"
    find_savefile("mateese")              --> "/save/m/mateese"
    find_savefile("no way")               --> 0