gcc 4.4 complains about some of the recovery ui functions not being
declared. To include the header, we have to fix the 'volatile'
declaration (otherwise there's a compiler error).
Move the dream-specific images to vendor/htc/dream, make the default
images a generic phone.
Take some device-specific details of the recovery UI (eg, what keys to
press to bring up the interface and perform actions, exact text of the
menu, etc.) and split them out into separate C functions. Arrange to
take implementations of those functions from the appropriate vendor
directory at build time. Provide a default implementation in case no
vendor-specific one is available.
