Use standard order for includes + Remove unnecessary boost/spirit include in format.hpp

@jpihl I fixed the include order here:
1. C/C++ standard headers
2. Boost headers
3. gtest headers
4. Dependency headers (if any)
5. Internal headers of this project
We should really write this down to the style guide to avoid any confusion.

It turns out that we had a missing <iostream> include in 4.1.0, and we did not release a bugfix for that. And this was exposed by the new boost release, so all the boost dependency checks are failing for the projects that use tables 4.1.0.
We should release tables 5.0.0 and update all projects. Then I can test the new boost ;)