XPloadFont()
  Load a text mode font into the EGA/VGA
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  Function:    XPloadFont()

               This function loads a font into the EGA/VGA
               card, which will be active in text Mode.
               Generally one would load a font in the 1st
               block (block 0, that is), but it is possible to
               load fonts into all blocks available (0 through
               XPmaxFonts()-1), and decide which one(s) should
               be active with XPsetFonts().

  Syntax:      XPloadFont(<BlockNr>,<Font>,<Rows>)

  Arguments:   <BlockNr> is a number between 0 and XPmaxFonts()-
               1, it indicates into which Font block to load.
               Block 0 can be used as default, that setting
               can be changed by XPsetFonts(). <Font> is a
               character variable of Size 3584 (14*256) for
               EGA adaptors, and 4096 (16*256) bytes for VGA
               adaptors containing all the characters
               definitions. The file EGAFONTS.DBF and VGAFONTS
               contain a number of sample fonts, but any
               varaible of that size (or file) could be used
               really. The <Rows> variable indicates how many
               rows are contained in one character. You should
               enter 16 for VGA and 14 for EGA, this redundant
               parameter is provided for compability with
               future extensions on this function.

  Returns:     Nothing.

  Usage:       * - Suppose we got A VGA..
               Use VGAFONTS index VGAFONTS
               seek 'HELVBOLD'
               XPloadFont(0,FONTDATA,16)