json-cpp Code

- Added basic string test (all char in ASCII range 33-126) and a large string test.

Forgot to add # to %g modifier for sprintf in valueToString for floats. Otherwise no decimal point appears when only zeroes would follow, which changes the type to integer.

Changed valueToString for floats so that zeroes after a decimal are truncated -- saves file size esp. for StyledStreamWriter which uses tabs instead of spaces.

Sketched out some idea to make the build system more reusable across projects.

Fixed compilation issue on windows (avoid using cstring and use string.h instead).

- rewrote doxygen documentation generation integration with Scons (still need some clean-up): list of sources is explicitly passed to a doxyfile builder which is used as input of a doxygen builder. Hence, the doxyfile depends on all the sources.
- documentation is now correctly generated once when source are changed on the first scons run.

Added rought roadmap.

Unneeded comment.

This file is auto-generated, even if it already exists. That is causing scons dependency problems, but the right answer is not to add the file, apparently.

added comment -- I always have to run twice to build docs because the doxyfile gets updated and causes scons to get confused. I do not know how to fix this, but I simply run 'scons doc/doxyfile' first.