INT 10 - VIDEO - UltraVision - LOAD USER FONT (EGA,VGA)
        AX = CD10h
        BH = bytes per character (08h,0Ah,0Bh,0Eh,13h,14h)
        CX = ABCDh load 9xN alternate font (v2+)
           else number of characters to load
                DX = character offset into font table
                DS:SI -> 8-byte ASCII font name
        ES:BP -> font definitions
Return: AX = FFFFh if invalid font parameters
Notes:  loads the designated characters into UltraVision's resident font area
        should be followed by a video mode set to reload character generator