Log exception if a command fails.
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 for some files 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
- Variable window becomes empty when 2 variable update vim commands are
  sent. So commented out the call to clear the window when thread
  resumes to get it working.