This improves the range of seeds compared to using only getMillis (which
is the number of milliseconds since program start) as the seed. This was
especially an issue if you started the game directly from command line,
Steam, or GOG instead of using the ScummVM interface. Previously the
initial seed was just the load time, which can have very small variance
on a fast computer.
Calling RandomSource::getRandomNumber() results in divide by zero
exception when called with max = 4294967295 as max + 1 overflows to zero
and the subsequent modulus operation causes the exception.
Certain game saves in Bladerunner trigger this.
This also removes the dependency of engines on the event recorder header
and API, and will make it easier to RandomSources that are not properly
registered.
