Add simple versioning handling when saving files

When quickly changing source code without CVS or the like it could be useful to save multiple BAcKup files with incremental or date&time in the name:
source.cpp
source.20101109182505.cpp
source.20101109182618.cpp
the options can include a limit in the number of backup files or in the days to keep backups and, when saving, the older files can be deleted.
In other words something similar to this previous giveaway http://www.giveawayoftheday.com/history-explorer-2-2/
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Yes, the idea was already requested on HippoEDIT forum.
Here is more details about it: http://forum.hippoedit.com/index.php/topic,213.msg769.html#msg769