Do not report non-existence of highlight icons on console

This deluges the log and the framework handles this case gracefully anyhow (by presenting the non-highlighted icon)
Safeguard against setting node cell title to nil which would raise assertion failure
Bugfix: Removed NSExceptions, as these cause crashes for apps that use Hockey. Also added a new sanity check in our all important _replaceNode… method. If inOldNode is no longer part of the node tree, then bail out early. This was probably due to a race condition.
Merge branch 'refs/heads/development'
Fix usage of library path to non-existent Lightroom library

This could happen after moving a library to another location via Finder.

Note that the fallback preferences key is "recentLibraries20" which is a list of libraries rather than a single library. And we are displaying the whole list then.
Merge branch 'development' of github.com:iMediaSandboxing/iMedia into development