Add json configuration saving/loading

[tbeswick96]

When merged this pull request will:

• Removed saveable type definer
• Remove usage of vanilla saving mechanism
• Removes need for saving fix mod
• Uses Newtonsoft.Json for (de)serialisation
• Sorting configuration separated out to own class
• Sorting configurations saved and loaded at same time as vanilla saving and loading, asynchronously
• Only maintains latest 50 saves to avoid file/memory bloat
• Closes #38