OpenSystemsDevelopment / qpdf

* Replace --create-from-json=file with --json-input, which causes the
  regular input to be treated as json.
* Eliminate --to-json
* In --json=2, bring back "objects" and eliminate "objectinfo". Stream
  data is never present.
* In --json-output=2, write "qpdf-v2" with "objects" and include
  stream data.

There are no automated tests yet, but committing work so far in
preparation for some refactoring.

These mean to leave the original values alone. This is needed for
reconstructing streams from JSON given that the stream data and stream
dictionary may appear in any order in the JSON.

I decided these were confusing and inconsistent with how JSON works.
They muddle the API rather than improving it.

Also add stubs for top-level QPDF methods (createFromJSON,
updateFromJSON)

Call the parent container's item method before calling the child
item's start method so we can easily know the current nesting level
when nested items are added.

moddify -> modify. Also carefully spell checked all remaining keys by
splitting them into words and running a spell checker, not just
relying on visual proofreading. That was the only one.

Not fully exercised in this commit

Update getJSON() methods and calls to them

The following script was used to adjust test data:

----------
#!/usr/bin/env python3
import json
import sys
import re

def json_dumps(data):
    return json.dumps(data, ensure_ascii=False,
                      indent=2, separators=(',', ': '))

for filename in sys.argv[1:]:
    with open(filename, 'r') as f:
        data = json.loads(f.read())
    if 'objects' not in data:
        continue
    trailer = None
    to_sort = []
    for k, v in data['objects'].items():
        if k == 'trailer':
            trailer = v
        else:
            m = re.match(r'^(\d+) \d+ R', k)
            if m:
                to_sort.append([int(m.group(1)), k, v])
    newobjects = {x[1]: x[2] for x in sorted(to_sort)}
    if trailer is not None:
        newobjects['trailer'] = trailer
    data['objects'] = newobjects
print(json_dumps(data))
----------

This commit just changes the order in which fields are written to the
json without changing their content. All the json files in the test
suite were modified with this script to ensure that we didn't get any
changes other than ordering.

----------
#!/usr/bin/env python3
import json
import sys

def json_dumps(data):
    return json.dumps(data, ensure_ascii=False,
                      indent=2, separators=(',', ': '))

for filename in sys.argv[1:]:
    with open(filename, 'r') as f:
        data = json.loads(f.read())
    newdata = {}
    for i in ('version', 'parameters', 'pages', 'pagelabels',
              'acroform', 'attachments', 'encrypt', 'outlines',
              'objects', 'objectinfo'):
        if i in data:
            newdata[i] = data[i]
print(json_dumps(newdata))
----------

Prevent my future self or other contributors from using assert in
tests and then having that assert not do anything because of the
NDEBUG macro.

This reverts commit dc059560e73e0b373a6e54e71b07e3af4b692cb4.

I changed my mind. There's no harm in leaving it deprecated for a
release cycle.