Implementation of #774 is mostly complete, but there is one minor inconsistency: whereas leading plus sign -- if (and only if) enabled as non-standard feature -- is retained for some floating-point numbers when accessing token with JsonParser.getText() (and related), it is not retained for any of integral numbers (nor all FPs).
The underlying problem to solve is that of assumptions based on there only ever being a leading minus sign in TextBuffer (or shared input buffer): something that made sense before allowing non-standard leading plus.