Intel errors with C 14 (icpc (ICC) 16.0.1 20151021)

1. for loop in constexpr function:

   /utils/const_string.h(55): error: statement may not appear in a constexpr function for (hash_type_t i = 0; i < size_; ++i) { ^

replacing this loop with static_for didn't work (as of 03.29.16)

2. std::index_sequence namespace bug:

static_for.h(33): error: namespace "std" has no member "index_sequence" void static_for(std::index_sequence<Is...>, F && f)

reported here: https://software.intel.com/en-us/forums/intel-c-compiler/topic/560329

therefore, instead of using utils::static_for we should better use static_for implementation from utils::container::static_for