chuck 1.4.2 appears to have broken Spectacle and Multicomb (RNG)

[dbadb]

chuck 1.4.2 appears to have broken Spectacle and Multicomb (RNG) by undefining RAND_MAX.

Seems like an opportunity to modernize and decouple. Both chugins want a rand2f function. Here's a simple+modern+portable one.

#include <random>
float rand2f (float min, float max)
{
    static std::mt19937 s_mt;
    static std::uniform_real_distribution<float> s_dist(0.f, 1.f);
    float x = s_dist(s_mt);
    return min + x * (max - min);
}

[gewang]

looking into this (@celestebetancur @nshaheed @gewang) we believe this is indeed due to rand2f using both ::random() and CK_RANDOM_MAX; the latter is determined by platform and may be inconsistent with ::random(); we plan to fix this post chuck-1.5, where we have a number of chugin evolutions on the roadmap.