minor bug: artillery shells management

[Rubik_Mind]

really wierd bug where ctrl+right click on my inventory artillery shells puts all of them in a chest instead of half of them.

[mmmPI]

This is because the artillery stack size is 1, similar with some armor, in such case the game tries to put "half" of each stack , and round up every time, so it put everything instead of "half of each stack".

[Loewchen]

85375