The 'type' field allows the rpc client to specify what type of ledger
entries to retrieve. The available types are:
"account"
"amendments"
"directory"
"fee"
"hashes"
"offer"
"signer_list"
"state"
"ticket"
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
* Generic functions to add entries to both object models.
* Add Json::Value into JsonObjects.
* Write Json::Value to string incrementally.
* Get rid of ripple::RPC::New namespace
