Upgrade lib::map container to red-black map

[ulmer-a]

The map container in the kernel support library is implemented as a plain and simple binary search tree. Nothing too complicated and works well. However, time complexity for the search operation could be improved by making the tree balanced (for example using a red-black tree, like in std::map).

This can be done independently from the rest of the kernel (no other kernel components need to be touched except map.h)