This works around some vv-fu you can use to pass in a config_entry to a proc that reads the value var of some other datum. Byond is stupid enough to actually read it, so it must be uniquely named.
* Consolidates datum var location
* Move ui_screen to /datum/tgui
* Move focusers to datum.dm. Move fingerprintslast to /atom
* Remove focusers list, makes mobs check if their focus is QDELETED in Life()
* Consolidate use_tag and var_edited into datum_flags
* Revert garbage comment
* Thought I already removed this
* Remove the var_edited preservation
* Removes focus QDELETED handling
