These changes make it unnecessary to copy header files around during
the build process, which tends to confuse IDEs and debuggers. The
headers which comprise Cantera's external C++ interface are now in
the 'include' directory.
All of the samples and demos are now in the 'samples' subdirectory.
Fixed a bug in the python interface having to pass vectors of integers.
They are now passed as doubles. This may not be fixed. It needs more
looking into.