The track design was recognised as a Corkscrew RC, not as a Hypercoaster. Moved the conversion code from the track design repository to the TD6Importer (where it should have been, really).
This also fixes the issue that Hypercoasters, Monster Trucks, Classic Mini Roller Coasters, Spinning Wild Mouses and Hyper-Twisters placed from a track design have the wrong ride type.
Fix the casing of 'isAllowedOnSlope' to match the way it is cased in the JSON files, which causes the flag to be read correctly and re-enables building on slopes for the scenery pieces which have it specified.
According to the [API docs](https://github.com/nlohmann/json/blob/develop/single_include/nlohmann/json.hpp#L23219-L23222), the fourth argument (which allows ignoring comments) was only introduced in version 3.9.0 (released on 27 July 2020), which is not present in Ubuntu 20.04 (it only has 3.7.3-1).
Since comments are not part of the JSON spec, this option is not terribly useful anyway. I have removed it, so that it can now compile on Ubuntu 20.04, and possibly also earlier versions.
Move functions in ObjectJsonHelpers to their relevant namespaces and classes
- Move ParseColour to Colour::FromString
- Move ParseCursor to Cursor::FromString
- Move LoadStrings to StringTable::ReadJson
- Move LoadImages to ImageTable::ReadJson
- Move ParseObjectEntry to Object::ParseObjectEntry
- Move GetString, etc. to Json::GetString, etc.
- Delete ObjectJsonHelpers .cpp and .h files
- Removed the ToJson(json_t) method
- The FromJson method expects to receive a JSON node of type object (as per added documentation)
- Unlike elsewhere, we need to use iterators for the Save() method to allow us to remove items from the array
- the body.dump() calls throughout use the default indent parameter of -1 so will produce JSON with no whitespace
- OnRegistrationReponse must be passed a JSON node of type object