Preserve mode on engine loading (sometimes)

Preserve mode on engine loading (sometimes)

That the mode always switched to EditGame after engine loading was
particularly annoying at the start of a game (where leaving BeginningOfGame
mode would disablethe Time Control dialog, and the engine would not
automatically reply if you start playing) and AnalyzeMode. These two
modes are now preserved, BeginningOfGame by refraining from calling
EditGameEvent() and sending 'force' to the new engine, and AnalyzeMode
be calling AnalyzeModeEvent() after the engine is loaded and repositioned.