chage API to be more consistent with C and Python API

we rename the following functions:
  set_will -> will_set
  clear_will -> will_clear
  set_login -> login_set
  start_loop -> loop_start
  stop_loop -> loop_stop
  set_callback -> callback_set
  read -> loop_read
  write -> loop_write
  misc -> loop_misc

This makes the API more consistent with the C and Python API. We keep
the old names for now, for not breaking current scripts.

Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>