Implement "holdover events," noting those log events which are not listed in the currently loaded log but which are present because they were playing when this log was loaded.

This fixes problems arising when the duplicate IDs thus introduced cause confusion.
Add a Clone button to create the 'same' Event just after the selected one
Insert Cart at the end of the log when no entry is selected
2014-09-24 Fred Gleason <fredg@paravelsystems.com>
	* Removed redundant line assignments in 'rdlogmanager/edit_clock.cpp'.
Merge branch 'tryphon-rdlogmanager-editclock-cloneitem'
2014-09-24 Fred Gleason <fredg@paravelsystems.com>
	* Removed redundant line assignments in 'rdlogmanager/edit_clock.cpp'.
	* Applied a patch from albanpeignier that adds a 'Clone' button
	to the 'Edit Clock' dialog in 'rdlogmanager/edit_clock.cpp' and
	'rdlogmanager/edit_clock.h' [GitHub pull request #000030].
Merge branch 'rdlogedit-editlog-insertattheend' of https://github.com/tryphon/rivendell into tryphon-rdlogedit-editlog-insertattheend
2014-09-24 Fred Gleason <fredg@paravelsystems.com>
	* Applied a patch from albanpeignier for RDLogEdit that appends
	a new cart to a log if 'Add' is touch with no long line highlighted
	[GitHub pull request #000031.
Merge branch 'tryphon-rdlogedit-editlog-insertattheend'
2014-09-24 Fred Gleason <fredg@paravelsystems.com>
	* Added code in 'rdlogedit/edit_log.cpp' to append a cart to the
	log when the 'End of Log' marker is double-clicked.
Merge branch 'holdover-fix' of https://github.com/smowton/rivendell into smowton-holdover-fix
2014-09-24 Fred Gleason <fredg@paravelsystems.com>
	* Applied a patch from smowton that fixed a clashing id problem
	when auto-refreshing logs in RDAirPlay [GitHub pull request #000028].
Merge branch 'smowton-holdover-fix'