local links do not work in .md
build dg.exe with C++ compiler, to allow extension in C++
toward optimising :map parameter type lists to avoid generating some separate derivations that are actually identical
toward optimising :map parameter type lists to avoid generating some separate derivations that are actually identical
now I believe have dg.exe outputting a DG where :map:xy drvedg has PrmTypLst with all (and only) relevant params to produce :xy (from something)
try to reduce map param types
slight adjustments to map tool param reduction so we do not crash on non-tool drvs