json-cpp Code

- added another parse interface taking a pair of const char *.
- removed unused header.

- doxygen tool: fixed bug in output (is env.Dir instead of File)
- added srcdist tool: generate tarball of source files. Dependencies retreival is still missing.

- added short introduction and build instruction.

- doc tarball now contains just the documentation folder and not the build directory.

- added simple targz tool.

- fixed bug in doxygen scons-tools (bad handling of windows path in configuration file)
- fixed bug in substinfile.py scons-tools (bad handling of windows path in substitution variable)
- doc version and output directory are now set by the build script.

- fixed compilation issue on msvc6 platform.

- integrated doxygen documentation generation in scons build system
- updated header.html to handle lastest doxygen (tabs in html)

- removed warning when compiling on msvc80.
- added (untested) support for iteration over object values or array values.

- Synchronized jsoncpp with integration in CppTL.
- Dependencies of Json::Value on std::map is now optional.