Started with a need for separate colouring of property names and values and blew out into this.
The folding is simple enough; doesn't fold on comments like LexCPP and tries a little to highlight malformed json controlled by the two options in the properties file.
Screenshot:

Props
Its time to make a new release so I’d like to defer this until after 3.6.4 is released.
The lexer code is missing, should probably be added to patch-scintilla.diff. If you are using Hg to make the diff, you need to "hg add" the new source code file.
A bit rash there
Thought you could post messages through email replies, sorry. Attached.
Committed as [b661b2], [4a9f94] with "json" added to SciTE's imports.exclude so that menus are not lengthened.
Related
Commit: [4a9f94]
Commit: [b661b2]