Python console:
* Add useful modules to the namespace during construction, rather than every time a snapshot is taken.
* Remove the namespace variables containing the snapshot of NVDA's state when the console is closed. Otherwise, these objects may potentially be held and not released for a very long time.
* Add some other modules to the namespace: os, sys, wx and api.
* Add brlRegions as a snapshot variable, which is the list of braille regions from the active braille buffer (braille.handler.buffer.regions).
