add a fix for the one problem case from the last commit: region splitting, where...

add a fix for the one problem case from the last commit: region splitting, where we don't announce regions until the entire edit op is done, but for naming purpoes each new region created needs to be in the map. likely that i will commit a better, cleaner fix for this later

git-svn-id: svn://localhost/ardour2/branches/3.0@12458 d708f5d6-7413-0410-9779-e7cbd77b26cf