Add boost-like Integer Type Selection

[TomSaw]

I quite often need a boost like Integer Type Selection. Currently for making modm::color pure generic.

Shall i port this or is there a another plan in the shelf?

[TomSaw]

Something like this:

template
struct smallest_uint
{
using type = std::conditional_t<
(Bits <= 8), uint8_t, std::conditional_t<
(Bits <= 16), uint16_t, std::conditional_t<
(Bits <= 32), uint32_t, std::enable_if_t<
(Bits <= 64), uint64_t>
>>>;
};

template
using smallest_uint_t = typename small_uint::type;

[salkinium]

Not sure if I'm ready to integrate boost, so I'd port it.

[TomSaw]

0kay i've kept it simple and added /modm/math/utils/integer_traits.hpp to #665 . It includes additional magic i needed for fully generic modm:ui:color.