[gsoc2020] Added bonus project to competency test

From: Mateusz Loskot (mateusz_at_[hidden])
Date: 2020-02-01 00:00:27

Dear students,

FYI, I have added a bonus project to the competency test for GSoC 2020.
It is described on the wiki page
https://github.com/boostorg/boost/wiki/Google-Summer-of-Code%3A-2020

Copied below:

Alternatively, bonus project that allows you to show your C++ skills
beyond usage of Boost.GIL:
Using C++11 type traits and Boost.MP11, define promote metafunction
that tries to
promote (find) fundamental integral type T (e.g. char, short, etc.) to
another integral type
with size roughly twice the bit size of T.

For example, for using P = promote<char>::type should assert the following
static_assert(std::is_same<P, short>::value) or possibly
static_assert(std::is_same<P, int>::value).

If you get stuck, don't hesitate to submit even partial solutions.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net