Cleanup: polish header masks and fix incorrect entries
Fix %USER_CA_CERT_* and %CA_CERT_ external_acl formating codes

  * The attribute part of the %USER_CA_CERT_xx and %CA_CERT_xx formating codes
    is not parsed correctly, make these formating codes useless.
  * The %USER_CA_CERT_xx documented wrongly
Fix tcp outgoing tos bugs part 3

Set tos and netfilter mark value for outgoing ftp data connections established
using the PASV command. Currently works only for EPSV command.
Register If-Unmodified-Since from RFC 7232
Docs: update HTTP header registrations
Fix typo in rev.13516
Docs: correct Proxy-Support code comment
Fix reconfiguration leaks: objects tied to http_port part1

This patch cleans up forgotten(?) clientca and crlfile PortCfg members.

Note: 
   PortCfg objects are still leaking so this change alone is not enough
Remove hierarchy_stoplist in favour of always_direct

This directive was deprecated 2 years (and versions) ago. It can be
replaced with:
  acl stoplist url_regex cgi-bin|\?
  always_direct allow stoplist

The major difference between the two configurations is that the old
hierarchy_stoplist was applied after never_direct and always_direct is
applied before it. Both override the never_direct result, so this is not
a problem.
Docs: cleanup obsolete directive listings
Docs: update release notes after rev.13524
Bug 4093: source-maintenance.sh bad perl -i option