json-cpp Code

- reorganizing repository to match standard layout

- fixed dist target build.

- ignore VTune paths.

- removed some warnings when compiling with gcc 4.1.

- added test to check empty member name { "" : 134 }.

- added some documentation
- added ValueAllocator to customize string duplication.

- updated build instructions
- integrated build instructions in html doc.

- added memory pool based allocator.

- added experimental StaticString support to avoid useless string duplication in Value constructor or member association.

- Value may now (optionally) use an internal hash-map and a simplified deque for objectValue and arrayValue storage.
- iterator related code extracted into src/lib_json/json_valueiterator.inl