- Fixes Paper and font tags stacking across rounds, as shown in: 
- Fixes Graffiti being persistent for over 50 rounds (10+ days)
- Sets Trash to be persistent for 4 rounds instead of 5
- Fixes Persistence being always-on because of if("persistence_enabled") config.persistence_enabled = 1. As explained:
> it's on by default, which means config.txt will be read and if it's not there it stays at 1. If it is there,it gets set to 1. There is no way to disable it
- Adds config options to enable/disable **Persistence for Maploaded objects**, as well as a verb to toggle such.
- Adds Persistence to config.
Currently IGNORE_MAPLOAD for Persistance is **Disabled.**
Maploaded objects/dirt/etc will be saved by persistence, preserving current behavior.
- Instead of using auto_use_power to re-tally up machinery's power usage every cycle, track the steady "static" load separately from the transient "oneoff" usage. Machines then only need to inform the area when they use oneoff power or *change* their steady usage.
- Remove auto_use_power and stop SSmachines from calling it.
- Add vars to track "static" usage for each of the three power channels to /area
- Rename the existing three vars to "oneoff" so its clear what they mean (and to catch people accidentally updating them directly)
- Update area power procs and APCs to use the new variables.
- Rename /area/proc/use_power() to use_power_oneoff() to make it clear what it is doing.
- Deprecate /obj/machinery/use_power() in favor of use_power_oneoff() but don't delete yet. Can transition gradually.
- Add logic to the update_power procs on machines to calculate the deltas and update static area power whenever their usage changes.
- Add logic to machines to update area power when they are created, destroyed, or move.
- Moved /obj/machinery procs related to area power usage into machinery_power.dm to make them easier to find.
- Added or updated comments in several places to explain what is going on and how to use it.
