json-cpp Code

- memory footprint of Json::Value is back to 16 bytes on WIN32.
(using bool allocated_:1 caused the compiler not to merge the attribute with the previous bitfield. Switched to int type to fix the problem).

- correct include path are now generated in the documentation.

- added (untested) accessors to get index or member name when iterating over members.

- added instruction to download and install scons-local.

- 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.