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
Source files are split to place all unit test code into translation
units ending in .test.cpp with no other business logic in the same file,
and in directories named "test".
A new target is added to the SConstruct, invoked by:
scons count
This prints the total number of source code lines occupied by unit tests,
in rippled specific code and excluding library subtrees.
