Fix closing and reopning rqt_bag topic views

This addresses several bugs:
 * It wasn't possible to close topic views when running standalone
 * If topic views were closed (non-standalone), it wasn't possible to
   open them again

This also moves the logic for handling open/close interactions out of
the TopicMessageView class, where they might not always be called, and
into the owning class instead
Merge pull request #230 from trainman419/fix_bag_topic_close

Fix closing and reopning rqt_bag topic views