- modified courier-imap-authmysql.patch

- modified courier-imap-authmysql.patch
  - security fixes around local part and domain validating functions
  - substitution variables parser rewritten from scratch
  - function pointers instead of messy stuff around parsing subroutines
  - added password string validators
  - fixed typo in an example config

Changed files:
    courier-imap-authmysql.patch -> 1.2
    courier-imap.spec -> 1.50