Moved ancillary files to extras/ (fixes #1011)

extras/tests/JsonObject/CMakeLists.txt

@@ -0,0 +1,23 @@
+# ArduinoJson - arduinojson.org
+# Copyright Benoit Blanchon 2014-2019
+# MIT License
+
+add_executable(JsonObjectTests 
+	containsKey.cpp
+	copy.cpp
+	createNestedArray.cpp
+	createNestedObject.cpp
+	equals.cpp
+	invalid.cpp
+	isNull.cpp
+	iterator.cpp
+	memoryUsage.cpp
+	nesting.cpp
+	remove.cpp
+	size.cpp
+	std_string.cpp
+	subscript.cpp
+)
+
+target_link_libraries(JsonObjectTests catch)
+add_test(JsonObject JsonObjectTests)