OpenSystemsDevelopment / qpdf

Add new private Util.hh header to define inline functions and expose as
ordinary functions in QUtil.

Remove member encoded and encode strings only when required.

Encoded is only used when writing JSON. Since most JSON writing is now
done on the fly without creating a JSON representation, creating and
storing the encoded string in almost all cases no longer serves any
purpose.

If duplicate keys are encountered, overwrite earlier values with the latest
value.

Create a simple utility class for writing JSON to a pipeline.

Using search and replace.

Recognise that JSON objects are effectively shared pointers to JSON_value.

Eliminate the use of shared pointers in JSONParser

Reduce boilerplate and increase efficiency by avoiding setting and
branching on action and ready in getToken.

Also, reject them in strings.

Handle all incomplete token type errors in tokenError.

(except '\\' and '\uXXXX')