Log Message:
Changes 3.5.17:
* nullptr is a C++11 feature
* Fix several ESI element construction issues
* SourceFormat Enforcement
* cachemgr.cgi: use dynamic MemBuf for internal content generation
* Add chained certificates and signing certificate to peek-then-bumped connections.
* Handshake Error: ccs received early: fix typo
* Avoid startup/shutdown crashes [by avoiding static non-POD globals].
* Bugs fixed.