Enable using the old envrionment variable passing of settings for json_process
so that the current autoconf test suite scripts can run nicely.
json_process now takes an optional command line parameter --env which
causes it to use the old method of reading the settings from
environment variables instead of directly from the "env" file.
Also added a --strip command line option, this will be used to
run the stripped tests with CMake as well.
* Now that JSON_SORT_KEYS is implemented, take it into use with the
valid and valid-strip suites. This is to ensure that the tests
remain valid even if the string hash function is changed in the
future.
* Remove test_dump API test. Instead, implement the same tests more
elegantly in the encoding-flags suite.