fix highest object screwups

generally code like this:

	for (i = 0; i < snis_object_pool_highest_object(blah)...)

should instead be:

	for (i = 0; i <= snis_object_pool_highest_object(blah)...)

So, we fix those mistakes.
make return work on text inputs
make selection of player ship render right
allow demon screen to plant spacemonsters