The threshold for printing species is a new, optional parameter to the
'report' function. If any species are excluded, the total number of
minor species and their aggregate mass and mole fraction are printed.
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.
