These modifications ensure enum.h can be used in a wider
selection of end user projects without triggering warnings.
GCC 4.9.2 was used with the following warning flags set:
-Wall -Wextra -Wshadow -Weffc++ -Wno-unused-parameter
-Wno-unused-local-typedefs -Wno-long-long -Wstrict-aliasing
-Werror -pedantic -std=c++1y -Wformat=2 -Wmissing-include-dirs
-Wsync-nand -Wuninitialized -Wconditionally-supported -Wconversion
-Wuseless-cast -Wzero-as-null-pointer-constant
This commit includes the modifications required to enable successful
use of enum.h via both the "test" and "example" directories.
