Have to define _DEFAULT_SOURCE before you can use the endian
conversion functions. As most standard library headers use
features.h, and _DEFAULT_SOURCE must be defined before features.h is
included, we have to include base.h before other headers.
Anything other than char (which can just use print.byte to print the
hex) and byte (which prints hexes anyway), all other types may be
forced to print a hex rather than a number if PRINT_HEX is 1.
These new members are just signed versions of the previous members.
This makes type punning and usage for signed versions easier than
before (no need for memcpy).
