hgweb: fixed invalid atom-log feed url in file log page
added comment TLS_PRIVATE_KEYFILE does not support Pass-Phrase
[config] added TLS_PRIVATE_KEYFILE to [imap|pop3]d-ssl
[impl] added TLS_PRIVATE_KEYFILE (OpenSSL)
[impl] added TLS_PRIVATE_KEYFILE (GnuTLS)
[doc] added TLS_PRIVATE_KEYFILE description
[GnuTLS] added non ssl error log when cert file does not exist
libgcrypt is required when --with-gnutls specified