DWDS/Dialing Concordance Code

+ mantis bug #19051 fix documentation querydoc.xml xml-ified (&, <)

+ mantis bug #19051 fix documented in querydoc.xml

+ mantis bug #19051 cleanup

+ mantis bug #19051: parse "6-er" as single symbol (problem: retain count #by[$l=1-1] --> [$l =1 -1])

* added server option StatsWindow : moving average window size
* added qtavg entry to 'status' response: average query time over last seconds
* added CDDCServer::m_SessionStats : track stats for local session
- serial mode: session stats added to server-wide m_ServerStats in CDDCServer::HandleClientConnection()
- client-thrads: session stats added to parent m_ServerStats in CDDCServerThread::run()
* factored out CDDCServerStats & co. from ddcServer.(h|cpp) to new ddcServerStats.(h|cpp)

+ factored out ServerStats.(h|cpp) from Server.(h|cpp)
- server statistics (administrative data)
- added new CDDCQueryTime, CDDCQueryTimeAvg for tracking most recent query-times over the last m_Window seconds
- TODO: work this into Server.h and get status to report it

* added CDDCServer::m_SessionStats : track stats for local session
- serial mode: session stats added to server-wide m_ServerStats in CDDCServer::HandleClientConnection()
- client-thrads: session stats added to parent m_ServerStats in CDDCServerThread::run()

+ split DDCTime into DDCTimeUnix + DDCTimeHiRes; generic wrapper typedef DDCTime respects DDC_USE_HIRES_CLOCK

+ tagged DDC-Concordance-0.35

+ v0.35: fixed DDC::PP::yyqlexer lexer bug with embedded quotes ('\'s')