The IDE include checker got to the point where it is actually useful and
this removes a lot of unneeded includes.
Naturally, especially for headers like util.h, this may mean we need to
re-add includes in consuming cpp files that bloats the diff a bit.
As we moved most of the creation of a BufferPool to be via the
Streaming::pool() method, which uses a thread-local, it makes sense
to start cleaning up the design and make it more modern C++.
The above mentioned method would return a reference and you'd see
loads of places use `auto &pool =` which is less than ideal.
As the number of places where we actually instantiate a BufferPool
goes down, the usage of some sort of smart pointer makes more sense.
This now makes all APIs use BufferPool be wrapped in a shared_ptr.
These are technically static libs, but not in any way shared libs.
They are used solely only by this repo and really only by the hub.
Most important, no header files are installed and basically none of
the normal rules for reusable libraries are applied to these files.
tomFlowee