reorder header
reduce rng engine dependencies
static assert now accept arbitrary message
static assert signees and size of result_type
static assert fp_type
move xorshfit_assign to rng/common.hpp
cleanup
more type safe
assert result_type of xor_combine
enable long long in C++98
fix for really large total
allow setting interval and leeway in start
stop now has a parameter `finished`
explicit initialize array data member