Removed JsonArray::is<T>(i) and JsonArray::set(i,v)

Removed `JsonObject::is<T>(k)` and `JsonObject::set(k,v)`
Replaced `T JsonArray::get<T>(i)` with `JsonVariant JsonArray::get(i)`
Replaced `T JsonObject::get<T>(k)` with `JsonVariant JsonObject::get(k)`

test/JsonArray/CMakeLists.txt

@@ -11,7 +11,6 @@ add_executable(JsonArrayTests
 	isNull.cpp
 	iterator.cpp
 	remove.cpp
-	set.cpp
 	size.cpp
 	std_string.cpp
 	subscript.cpp