Several changes mixed to one commit (sorry, the CVS didn't work for a long time):

Several changes mixed to one commit (sorry, the CVS didn't work for a long time):

o  Changed index format ID.
o  MAX_COMPLEX_LEN went with the rest of complexes.
o  Introduced data types and handling macros for context bucket ID's.
o  Returned fp_hash() to its original definition -- the previous "fix" was
   deadly wrong: I confused indexing of bytes with indexing of words.
   Also, the fp_hash() has to be monotonic wrt. fpsort's order which the
   new one wasn't.