An alternative to the unity build, the classic build compiles each
translation unit individually. This adds more modules to the classic build:
* Remove unity header app.h
* Add missing includes as needed
* Remove obsolete NodeStore backend code
* Add app/, core/, crypto/, json/, net/, overlay/, peerfinder/ to classic build
* Use signal_set as cross platform way of handling SIGINT
* Remove polling on main thread for shutdown.
* Add extra logging for received signal.
* Clean up exit handling on error in setup routines.
* Reuse isStopped() from Stoppable for status (could be isStopping() instead).
* Ctrl-C should now work for standalone mode as well on Windows.
Also small fixes to Resolver:
* Add Resolver prefix to logging.
* Fix AsyncObject::removeReference() logic.
* Fix work remaining logic.
* New src/ripple/crypto and src/ripple/protocol directories
* Merged src/ripple/common into src/ripple/basics
* Move resource/api files up a level
* Add headers for "include what you use"
* Normalized include guards
* Renamed to JsonFields.h
* Remove obsolete files
* Remove net.h unity header
* Remove resource.h unity header
* Removed some deprecated unity includes