Implemented support for arbitrarily sized Raw template unions
* BinaryMapping tuples are not limited by integral types anymore
* makes mapping a wider range of plain structures possible
* Raw template is a union template with a byte array member
* Support for unions was already added to sorters in commit d6b94cc
* Added basic test cases for Raw<> unions
* Currently warnings are generated when specifying the array content using the variadic raw constructor because the values are narrowed down to fit into uint8_t