json-cpp Code

- Documentation generation is no longer handled by SCons. The script doxybuild.py is used to generate the documentation on demand.
- Added file 'version' that contains jsoncpp version number. It is used by both SConstruct and doxybuild.py.
- Updated README.txt with documentation build instruction, and instructions to add a test case.

- added missing virtual destructor to TestCase.

- added command-line option --with-json-checker to run test from jsonchecker test suite of json.org.

- updated roadmap (utf-8 handling in Reader)

- added Int/UInt typedef in Json namespace. Modified Value::Int and Value::UInt to be typedef on those. Modified code to use Json::Int instead of Value::Int.
- added Value constructor taking begin/end pointer to initialize the Value with a non-zero terminated string.

- added a large test that cause(d?) crash with experimental JSON_VALUE_USE_INTERNAL_MAP

renamed jsontestrunner.py to pyjsontestrunner.py to avoid confusion

- fixed failing test

Integrated part of Patch #2839016, fixing default iterator initialization when using internal map.

Added another failing unicode test case