This allows construction of basic_format_args from a dynamic set of arguments. The syntax is a little clunky and could probably be improved but this at least enables the functionality.

This reverts commit 0eb01b83.

https://godbolt.org/g/rpiDgh

This reverts commit f9e9bf02.

Added enum colors conversion to rgb struct.
Added colors_test.cpp.

Removed print_colored.
Renamed enum colors back to color.

Removed unnecessary inline keyword.
Removed print_rgb.