Flight time debugging

Added an option to the octree servers to print out additional usecTimestampNow() debug info every 10 minutes (if requested)... this is to help track down the unreasonable flight time messages that are still happening when a server runs for over 12-20 hours.
This is a lot of debug logic that bloats the instruction length of the usecTimestampNow() implementation theoretically helping to break CPU cache coherency whenever it is called, and thus makes usecTimestampNow() an even less desirable method for loops that require high performance.  Perhaps we should have a nice fast usecTimestampNow() method and debugUsecTimestampNow() implementation for those few parts of the code that need it.