Added tests to default build target.
Added build options (-fPIC) for library.
Create laft::core::Mixin. An utility class used to implement mixin that need some functions or attributes of the concrete class.
Created an Output mixin. The wrapper methods it provide allow to write bytes in multiple ways.
Implemented laft::core::StringOutput. This class will be used to build string with the same operations used to write to a file.