Ehrhart polynomial: k >= 1

Signed-off-by: Nicolai Hähnle <nhaehnle@gmail.com>
Small fixes and clarifications

Signed-off-by: Nicolai Hähnle <nhaehnle@gmail.com>
Note convolution and Hadamard bound

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