mcpp V.2.6.4 released

MCPP V.2.6.4 was just released.

MCPP is a portable C/C++ preprocessor, supporting GCC,
Visual C++, etc. Its source is highly configurable and can
generate executables of various specs. It accompanies a
validation suite to check preprocessor's conformance and
quality exhaustively.

The updated points from V.2.6.3 are as follows.

1. This is a bug-fixed version of V.2.6.3, fixing memory
leaks in subroutine-build, and fixing a bug of accessing
non-allocated memory.

2. Also changed the installation directory of some documents
in stand-alone-and-compiler-independent-build by
configure or by binary packages.