orrect use of Stirling's approximation in certain multiprecision cases,
          fixes <a href="https://github.com/boostorg/math/issues/396" target="_top">#396</a>.
        </li>
<li class="listitem">
          Eliminate -Wimplicit-int-float-conversion on clang.
        </li>
<li class="listitem">
          Fix some constexpr issues in quaternion/octonion.
        </li>
<li class="listitem">
          Minor performance fix to tanh_sinh integration.
        </li>
<li class="listitem">
          Update hyper