This upstream refactor stopped passing in the pool by pointer and
now wraps it in a shared_ptr.
A lot less 'address-of' operators and generally cleaner code are
the result.
Fixes: #16
* Don't store the initial dummy value '100,-' in the history.
* Don't store the 404 server reply as a price file.
* On switching of currency, instantly try downloading the
historical prices instead of waiting for the next restart.
The backend has the historical prices in its database, we ask for it by
timestamp the by default it returns the nearest value. Typically within
24 hours.
But if the database doesn't have the data, or its very inaccurate, this
may casue confusion.
So we now have a new API call that returns zero instead of an inaccurate
historical price. Allowing us to prefer not showing anything over plain
false data.
Slowly the amount of cpp sources has been growing to the point
where its just too much to store in the root of the project.
I think they are more happy in a subdir as well, getting an elevated
position for themselves.