Begin chapter on generating functions

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Triangulations and basic definitions of algebra of polyhedra

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Generating functions and Euler characteristic

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Some copy-editing

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Signed decompositions and Brion's theorem

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Evaluation of f(P;1) and some copy-editing

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>