* Standardizes cleaning item functionality into "cleaning_act" proc
* Culling commented-out code
* Damp rag now checks for humans before cleaning
* Change proc scoping, moved mop reagent check out of cleaning.dm
* Adds can_clean and post_clean procs to handle mopping, removes ismop parameter
* Adds can_clean() to cleaning objects/mobs
* cleaning_act() now carries message strings as params
* Refactored cleaning_act() for earlier returns and less redundancy
* cleaning_act now runs on the target atom, instead of the cleaning object
* Changed turf checks to overrides, rescoped clean_turf, lots of tidying
* Removed cleaner param from post_clean, since it'll always be src
* Code review tidying
* Tidying..........
* Removed clean_turf and put its functionality in turf/simulated/cleaning_act(), added new param to keep track of original targeted object
* Moved cleaning.dm from datums to code/game/objects
* Added early return, defined cleanspeed in seconds
