Also:
- Use {}-style list initialisation for SourceLocation construction
- Introduce new system includes
- Changes the API of the Scanner to take source as value (with move) as opposed to as a reference
This change is made to (easily) be forward compatible with future C++
standards, in order to allow compiling the code with newer standards at
some point in the future.
* Removed the `using byte = uint8_t;` line from Common.h
* Mechanically change all uses of `byte` to `uint8_t`.
Tested with GCC 7.3 in C++11/14/17 modes :-)
