Implement virtual DebugSession::killDebuggerNow()
Once kdevelop!182 (merged) is merged into 5.6, this change will be necessary only in kdev-xdebug master.
kdev-xdebug compiles with this change. All tests (2) pass: appstreamtest, connectiontest. Sorry, I haven't tested how this commit works, because I am not a PHP developer and have zero experience with kdev-xdebug.
See the commit message for details.