Remove unused functions from wrappers

The getChildren and derefernce functions are never callled. Also the member
self.variable was renamed some time ago and would have led to crashes but
because it was never called we did not notice.
Merge pull request #45 from giselher/variables-fix

Remove unused functions from wrappers
Use getitem magic method instead of getattr

Add the __getitem__ magic method to the VariableWrapper class because the
__getitem__ string inside __getattr__ does not work.

Also fix formating and redundant comment
Merge pull request #46 from giselher/variables-fix

Use getitem magic method instead of getattr
remove redundant backslashes
don't die on =breakpoint-created response

A =breakpoint-created response will be sent by gdbs with the feature
"breakpoint-notifications" when the user adds a breakpoint using the CLI.

Note that the response is NOT handled correctly yet -- the parser just does
not die if it is encountered.
don't use logging in parser which runs in a different thread

Logging, in combination with the handlers we're using, will use widgets to
show the errors. Messing with GUI elements from different threads is not
allowed, however; therefore, this would result in a crash.