Function:     xBxx()
Purpose :     Draw a box on the screen with attribute and optional shadow
Usage   :     Bxx(<expN1>, <expN2>, <expN3>, <expN4>, <expN5>, <expN6>, ;
                   <expN7>,<expC1>,<expn8>,<expn9>)
Params  :     expN1 - top row
              expN2 - left col
              expN3 - bottom row
              expN4 - right column
              expN5 - attribute of box
              expN6 - numeric shadow type  (default 0 - no shadow)
                      follow numeric keypad     |  7 8 9
                                                |  4 5 6
                                                |  1 2 3
              expN7 - shadow attribute (default 7 - grey on black)
              expC  - frame string - MUST be 8 characters - default single
              expN8 - explode speed factor 1-1000 (depends on machine)

              All params MUST be passed. For numerics, pass -1 for default.
              For string, pass '' for default.

Returns :     nothing.
Found in:     xbxx.c