fix MSVC configure
vSMCFindRandom.cpp no longer test discrete_distribution
WeightSet::draw no longer use discrete_distribution
avoid type conversion in cl_set_kernel_args
rng/defines.h include cmath/math.h if used in C/C++
workaround MSVC 2010 bug
test all C++11 engines
DummyStopWatch return at least 1ns to avoid possible divide by zero
update examples