Previously fread and fwrite for file descriptors would return the number of
bytes read/written rather than the number of elements read/written. This
breaks the C standard and broke various third party programs such as
readelf from binutils.
C and C++ files are now kept together and so are the mxmpp declarations.
Header files are now stored in include/ and mxmpp'd into preproc/.
All other code now -I ../libmaxsi/preproc.
And other stuff to make this happen, including refactoring Makefile.
