Returns the value associated with key under group_name as a
boolean.
If key cannot be found then FALSE is returned and error is set
to G_KEY_FILE_ERROR_KEY_NOT_FOUND Likewise, if the value
associated with key cannot be interpreted as a boolean then FALSE
is returned and error is set to G_KEY_FILE_ERROR_INVALID_VALUE
Returns the value associated with key under group_name as a boolean.
If key cannot be found then FALSE is returned and error is set to G_KEY_FILE_ERROR_KEY_NOT_FOUND Likewise, if the value associated with key cannot be interpreted as a boolean then FALSE is returned and error is set to G_KEY_FILE_ERROR_INVALID_VALUE