Proposal to update the VHDL 2008 packages to fix identified bugs and errors.

1) fixed_generic_pkg-body.vhdl
Modify the following procedures:

  procedure add_carry (
    L, R   : in  UNRESOLVED_ufixed;
    c_in   : in  STD_ULOGIC;
    result : out UNRESOLVED_ufixed;
    c_out  : out STD_ULOGIC)

  procedure add_carry (
    L, R   : in  UNRESOLVED_sfixed;
    c_in   : in  STD_ULOGIC;
    result : out UNRESOLVED_sfixed;
    c_out  : out STD_ULOGIC)

in each of these modify line assigning "c_out" to be as follows:
  c_out      := result_slv(left_index-right_index);


2) float_generic_pkg-body.vhdl
a) Modify the following functions:

  function to_float (
    arg                     : UNSIGNED;
    constant exponent_width : NATURAL    := float_exponent_width;  -- length of FP output exponent
    constant fraction_width : NATURAL    := float_fraction_width;  -- length of FP output fraction
    constant round_style    : round_type := float_round_style)  -- rounding option
    return UNRESOLVED_float

  function to_float (
    arg                     : SIGNED;
    constant exponent_width : NATURAL    := float_exponent_width;  -- length of FP output exponent
    constant fraction_width : NATURAL    := float_fraction_width;  -- length of FP output fraction
    constant round_style    : round_type := float_round_style)  -- rounding option
    return UNRESOLVED_float

Mofify the "arg" argument in both functions to be "UNRESOLVED_UNSIGNED" and "UNRESOLVED_SIGN".
The type of the "XARG" variable must be modified accordingly.

b) Modify the following function:

  function to_float (
    arg                     : UNRESOLVED_sfixed;    -- signed fixed point
    constant exponent_width : NATURAL    := float_exponent_width;  -- length of FP output exponent
    constant fraction_width : NATURAL    := float_fraction_width;  -- length of FP output fraction
    constant round_style    : round_type := float_round_style;  -- rounding
    constant denormalize    : BOOLEAN    := float_denormalize)  -- rounding option
    return UNRESOLVED_float

Modify the variable "arg_int" to be as follows:
    variable arg_int     : UNSIGNED(integer_width - in_fraction_width
                                    downto 0);  -- unsigned version of argument
Modify the variables "exp" and "exptmp" as follows:
    variable exp, exptmp : SIGNED (exponent_width + 1 downto 0);
Modify the assignment of "arg_int" on line 2924 from "argx := -argx;" to:
        arg_int := UNSIGNED(to_x01(not STD_LOGIC_VECTOR (argx))) + 1; -- Make it positive with two's complement
Modify the assignment of "arg_int" on line 2927 to the following:
        arg_int := UNSIGNED(to_x01(STD_LOGIC_VECTOR (argx))); -- new line: direct conversion to unsigned

c) Fixed point documentation:
Fixed the size returned by the signed reciprocal in Table xxx