Improvements to breakpoint commands.

* Created separate commands to add, remove breakpoints instead of using
  the toggle command. The toogle command has been disabled since it
  should really be used to enable/disable breakpoints; not create them.
  This will be enabled later.

* To follow the same convention, separated the suspend and resume
  commands to have a suspend all, resume all command.

* Updated doc to reflect new commands.

* Bug fix to update the debug status threads when the debugging session
  is disconnected because the remote VM terminated.