gras: make ptree usage optional on old boosts
gras: work on module loading and python factory

naming convention, path convention, env var convention,

And, make a python factory -- but its a little halfassed.
You see, we didnt do the swig director thing yet,
so C++ cant yet create python blocks from the factory.
Merge branch 'master' into gras_tool2
gras: tweaks to GRAS TOOL as we use it in extras