added new behaviour of NIn to correct for var assigment, still small issue in reversegraph
corrected small error in markalloc
NIn now differentiated, fusenodes corrected
corrected NSRef dispatch, started order > 1
improved nth order diff
started nth order for vector params
some progress on nth order
slight progress on nth order
weird results 2nd order, ...
unified main field of all NRef and NSRef, tweaked simplifcations
corrected deriv bug for NSRef, order 2 seems ok but failure for order 3
last statement now correctly handled, allowed piping between prune, simplify and splitnary
rewrote order 2+, still failure for order 3
order 3 bug still elusive
new tests on order 3, missed link for loop index ?
added doc and test_syntax.jl
added linhk to the doc url
added rdiff for function but not fully working
corrected doc on rdiff
added internals chapter to doc