What's new in at-spi2-core 2.3.91:

* Invalid states when receiving a focus event (BGO#663992).

* Fix atspi_table_get_row_column_extents_at_index.

* Expect a signed in tfor GetIndexInParent, per the spec.

* Send key events to listeners assumed to be hung, but don't block.

* Reduce the method call timeout slightly, so that it will be lower than
  the keystroke listener timeout.

* Don't cache data for transient objects.

* Enable caching on a call to atspi_accessible_set_cache_mask, even if
  atspi-event_main() hasn't been called.