encoding/FLOAT

    Floats consists of [encoding/INT]-encoded mantissa "m" and
    base-2 exponent "e": m * pow(2,e).

    Normalised values *must* be used.
    Separate tag's values are used for representing NaN and infinite
    numbers. Zero is represented as zero mantissa and exponent.

                NaN = 0x10
               +inf = 0x11
               -inf = 0x12
        float(m, e) = 0x13 || INT(m) || INT(e)
                0.0 = float(0, 0)

    That representation is far from being compact. Sending binary IEEE754
    binaries may be more preferable.

    Example representations:

    NaN                              | 10
    +inf                             | 11
    -inf                             | 12
    0.0                              | 13 0C80   0C80
    45.25   m=181 e=-2               | 13 0C81B5 0D8101
    -45.25  m=-181 e=-2              | 13 0D81B4 0D8101
    0.125   m=1 e=-3                 | 13 0C8101 0D8102
    0.15625 m=5 e=-5                 | 13 0C8105 0D8104
    123.456 m=8687443681197687 e=-46 | 13 0C871EDD2F1A9FBE77 0D812D