Update changelog: sets.scrollLists* preferences
rs.loadSubScript(): fix typo in deprecation warning
Add pu.get() and pu.set(), deprecate pu.pref() and pu.readPref()
Replace all pu.pref() calls with pu.get()/set()
ut._err(): don't use deprecated function.caller
pu.pref(), pu.readPref(): add deprecation date