Support a relaxed casting mode

[cyanreg]

Currently, if you want to set any limited-precision number in any situation, you have to cast.

    uint16_t val = uint16_t(0);
    const uint16_t arr[4] = { uint16_t(0), uint16_t(0), uint16_t(0), uint16_t(0) };

This leads to code interacting with mixed-precision numbers requiring casts in every single line, such as throughout this entire file.

Everything here was designed to not overflow. Generally programmers know whether something will overflow or not.
Having a #pragma releaxed_casting would be a good quality of life improvement.

[arcady-lunarg]

Note that for the specific case of integer literals you can write your example code as

    uint16_t val = 0us;
    const uint16_t arr[4] = { 0us, 0us, 0us, 0us };

which is at least somewhat less annoying to write though of course still requires you to keep track of the types. Does that help at all?