Also included is an additive lagged fibonacci generator that should is
very similar to EQ's. Also added BIASED_INT_DIST in case someone wants
to use "bad" int distribution to more closely match EQ as well.
An option to set a custom engine (just in case people would like to play
with other std engines) is available.
There is also support for GCC's SIMD accelerated extension to std random
engines.
All these options are hidden behind advanced options in CMake since
they're rather advanced knobs.
