Remove JSON Spirit wrapper, remove JSON Spirit leftovers

- implement find_value() function for UniValue
- replace all Array/Value/Object types with UniValues, remove JSON Spirit to UniValue wrapper
- remove JSON Spirit sources

src/Makefile.am

@@ -182,17 +182,6 @@ BITCOIN_CORE_H = \
   zmq/zmqpublishnotifier.h
 
 
-JSON_H = \
-  json/json_spirit.h \
-  json/json_spirit_error_position.h \
-  json/json_spirit_reader.h \
-  json/json_spirit_reader_template.h \
-  json/json_spirit_stream_reader.h \
-  json/json_spirit_utils.h \
-  json/json_spirit_value.h \
-  json/json_spirit_writer.h \
-  json/json_spirit_writer_template.h
-
 obj/build.h: FORCE
 	@$(MKDIR_P) $(builddir)/obj
 	@$(top_srcdir)/share/genbuild.sh $(abs_top_builddir)/src/obj/build.h \
@@ -233,7 +222,6 @@ libbitcoin_server_a_SOURCES = \
   txdb.cpp \
   txmempool.cpp \
   validationinterface.cpp \
-  $(JSON_H) \
   $(BITCOIN_CORE_H) \
   $(LIBZCASH_H)