introducing feature/instdir - "installing" change (not finished)

Hi there,

Thanks to David's work on instdir and filelists (Julien was helping
out and probably also others, thanks!) we now produce instdir/
directory during build which is almost the same as install/ after make
dev-install.
So, when feature/instdir is merged, there should be no need to run
make dev-install - if you are a simple developer who just wants to run
soffice.

Could someone please test feature/instdir for other platforms,
possibly also for Linux ?
It most probably does work only on Linux now, but should be easy to
fix - only few variables I suspect.
Well, smoketest's extension test fails also for me unfortunately :-(
Ideally what you would check:
- install/ produced in 5722cc4b075397f312ad9366539b73bc310bfd34~ and
in 87bea8266ca1e3877ad961555b33d99b1317f63c is the ~same
- diff -rq install instdir/*/ does not show differing files, only some
(not important) missing ones

open questions:
- How does this impact tinderboxes / What install-tb: should do
- What's MACOSX_CODESIGNING_IDENTITY thing in dev-install target -
should we move it to instsetoo_native/ as a custom target probably ?

Ideally, someone (more people) now step in and finish the work ;-)

Thanks,

Matus