Remove unused SHAMap::getItem
Add missing beast includes
Move nodestore to its own module
Tidy up includes:
* Replace boost with std equivalents:
  - bind, ref, cref, function, placeholders
* More "include what you use"
* Remove unnecessary includes
Remove ScopedPointer, ContainerDeletePolicy
Tidy up basics module:
* Move directory up
* Remove unity includes and "include what you use"
Autobridging:
* Remove legacy OfferCreate transactor
* Misc. cleanups
* Fix a subtle bug with arithmetic operations on Quality
* Sanity check offers after taking