3.2.0 - Composer and AddressSplitter under scrutiny

• Made Compose/*Builder classes *AddressSplitter field protected so extending classes can change that field.
• AddressSplitter uses isFirstByte() for byte sorting
• Fixed parsing composer WriteRegisterRequest and WriteCoilRequest requests - they should act as composer Read*Request classes and return an array (empty in this case). Composer\Write\Register\WriteRegisterRequest and Composer\Write\Coil\WriteCoilRequest method Parse now returns array|ErrorResponse as interface implementation should.