Fix incorrect use of ObjectDeleter.
Add "Run to cursor" context action.

- UserInterfaceListener/TeamDebugger: Extend ThreadActionRequested()
  to allow passing a target address. Adjust TeamDebugger's
  implementation accordingly.

- ThreadHandler: The MSG_THREAD_RUN action can now optionally take an
  address parameter to run until. If this is specified, set a temporary
  breakpoint for said address before resuming execution.

- SourceView: On right click, present a context menu showing possible
  actions for the current line if we're currently in a stopped thread.
  For the moment, this only yields the "Run to cursor" action, but
  more will be added in the future.