Added a new PRNG library to replace <random>.

Added a new PRNG library with interfaces described in
<up/random.hpp> This Library more or less emulates some of the
basic C++11 random number facilities, but optimized to avoid
memory heap allocation. Current generators include 64-bit and
128-bit xorshift implementations.

The upcore benchmarks project now compiles on Linux with GCC 4.4
as a result of this work, as this target was missing the <random>
header file (only the TR1 variant was available).

Also removed the allocate_throw/malloc_throw functions as it
wasn't deemed necessarily (most usecases of Upcaste will have
exception handling disabled).