R_FntFile()
 Install an external EGA or VGA font from a disk file
------------------------------------------------------------------------------

 Syntax
        nRetCode := R_FntFile ( cFileSpec )

 Arguments
        cFileSpec       File specification of a font file.
                        Format : [d:][\path\]filename[.ext]

 Returns
        nRetCode        Return code
                        0 - FL_OKAY             No errors detected
                        1 - FL_INVALID_PARMS    Invalid parameters passed
                        2 - FL_ALLOCATE_MEMORY  Error allocating memory
                        3 - FL_ERROR_OPENING    Error opening font file
                        4 - FL_ERROR_READING    Error reading font file

                        N.B. the return codes are pre-defined in the header
                                file RFntLib.CH

 Description
        With the function R_FntFile () you can load and install an EXTERNAL
        font from a font file.
        The size of the font files may be :
        3584 bytes for an EGA font
        4096 bytes for a  VGA font
        The font files can be created/manipulated using the RFntEdit
        program that comes with the RFntLib library.

        +----------------------------------------------------------------+
        |                         -+- CAUTION -+-                        |
        |                                                                |
        |     IN THE UN-REGISTERED  VERSION OF RFNTLIB THE FOLLOWING     |
        |     REGISTRATION MESSAGE WILL BE DISPLAYED AT RANDOM TIMES     |
        |     (WHILE EXECUTING THE R_FNTFILE FUNCTION) :                 |
        |                                                                |
        |     Unregistered version of RFntLib - Wait for 8 seconds.      |
        |                                                                |
        |       AFTER A 8 SECONDS DELAY THE PROGRAM WILL CONTINUE.       |
        +----------------------------------------------------------------+

 Example
        *-- Install a font called RSYMBOL1.RFV
        #include "RFntLib.ch"

        LOCAL   nRetCode

        nRetCode := R_FntFile ( 'RSYMBOL1.RFV' )

        DO CASE
        CASE nRetCode = FL_INVALID_PARMS
                Alert ( 'Invalid parameter(s) passed to R_FntFile().' )

        CASE nRetCode = FL_ALLOCATE_MEMORY
                Alert ( 'Not enough memory ...' )

        CASE nRetCode = FL_ERROR_OPENING
                Alert ( 'Error opening font file (file not found ?).' )

        CASE nRetCode = FL_ERROR_READING
                Alert ( 'Error reading font file.' )

        ENDCASE