Bug fix for breakpoint toggle and variable window updates.

These are temporary workarounds.

Breakpoint window
- Project name is displayed as part of location list. This is sent
  back while toggling breakpoint.
- But for some projects, ICompilationUnit of a file is not
  existing. So we iterate over all breakpoints and toggle the matching
  one. If this does not match, then use the old way of querying using
  project name and file name.

Variable window update
- For some reason, VIM buffers a remote command instead of executing it.
  This is happening when we send updates to variable window. The first
  update clears the screen and the second update sends the new set of
  variables. But 2nd update gets buffered in some cases. To workaround
  this, we send another remote command to echo an empty string. This
  forces VIM to execute the previous command.