Update: Lay out the foundation for proper endianness support.

Update: Lay out the foundation for proper endianness support.

The endianness support is not currently a direct goal of the 0.4 versions.
The 0.6 versions will deal with networking and will most certainly need proper endianness support.

Ultimate the FLL needs to properly handle endianness.
Provide the initial functionality needed to make this possible.

The BIG_ENDIAN and LITTLE_ENDIAN cannot be directly relied on.
Provide custom _is_F_endian_big and _is_F_endian_little macros where when BIG_ENDIAN is not defined default to little endian.
By using the custom _is_F_endian_big and _is_F_endian_little, allow for the endianness to be explicit set at compile time.
This should make it easy to configure in cases where BIG_ENDIAN and LITTLE_ENDIAN are not defined.