reduce tests passed for wip-v0.5
renew codegen
macro compose_reducedim
modified reducedim.jl
new reducedim framework working for basic functions
mean along dimensions tested
basic functions tested over strided views
more tests on reduction kernels
reducedim with functors tested
add reducedim back to test suite
folddim reinstated
reinstate benchmarking on reductions
reinstate norms (not tested)
add reduce + mapreduce
reducedim + mapreducedim
norms re-tested
statistics re-tested
wsum reinstated
pdmat reinstated