New system headers in C++11/14

Some short examples introducing C+11/14-features of the STL.

Containers:

<array>
<forward_list>
<functional>
<initializer_list>
<tuple>
<unordered_map>
<unordered_set>

Concurrency:

<atomic>
<condition_variable>
<future>

Other:

<chrono>
<cstdint>
<random>
<regex>
<type_traits>