Optimised functions to read and write int16/32/64 from strings, bytes and bigarrays, based on primitives added in version 4.01. The library implements three modules: * EndianString works directly on strings, and provides submodules BigEndian and LittleEndian, with their unsafe counter-parts; * EndianBytes works directly on bytes, and provides submodules BigEndian and LittleEndian, with their unsafe counter-parts; * EndianBigstring works on bigstrings (Bigarrays of chars), and provides submodules BigEndian and LittleEndian, with their unsafe counter-parts.