Add some more callbacks for root properties (bug #42347). * graphics.in.h (root prop. errormessage): set read-only and declare custom get method * graphics.in.h (root prop. diary, diaryfile, echo, recursionlimit): declare custom get/set methods * graphics.cc (root::properties::get_errormessage, set_diary, get_diary, set_diaryfile, get_diaryfile, set_echo, get_echo, set_recursionlimit, get_recursionlimit): new methods. * pager.cc (F__diaryfile__, F__diarystate__): new functions to retrieve diary info. * pager.cc: set default value "diary" for diary_file static variable. * input.cc (F__echostate__): new function to retrieve echo info.