Merge branch 'ua/atoi'

Replace various calls to atoi() with strtol_i() and strtoul_ui(), and
add improved error handling.

* ua/atoi:
  imap: replace atoi() with strtol_i() for UIDVALIDITY and UIDNEXT parsing
  merge: replace atoi() with strtol_i() for marker size validation
  daemon: replace atoi() with strtoul_ui() and strtol_i()