add refresh task for docs

once the SDK is already built, we don't need to recompile the whole SDK,
we only need to recompile the loomlibs to regen the docs.
trace progress through the class packages

it can take a few minutes, so it's nice to see some progress updates
along the way.
shorten descriptions to fit on windows console
improve / correct version checking; make platform independent

fixes LOOM-659
use replace instead of reassignment to avoid warning

(we can change the constant instead of redefining it)
relocate the load path edit so the trace appears at a better spot

(instead of in the middle of the configuration variables)
add proper filelist pre-reqs for docs; only open on supported OSes
use file prereqs properly, to avoid rebuilding when unnecessary
Merge pull request #179 from ellemenno/docs/PBG-SimplerDocTasks

simpler doc tasks