Better UI for displaying decremented uses of things

[symposion]

Currently there's no consistency between the death save output (not pre-decremented by the sheet but really needs to be, since the up-to-date count is the most relevant information to display), the uses for traits (not pre-decremented by the sheet, but that makes a certain amount of sense), ammo (pre-decremented by the sheet) and spell slots (not displayed at all). I think we need to decide what the correct UI is for the different cases. In the cases of trait uses, ammo, and spell slots, I'd argue that the sheet should output the current, un-decremented value by default + the per_use value where applicable. There should then be options to enable script processing for each; if this is enabled, the sheet should display only the per_use value and the script should then output an addendum giving the remaining value.