Use URE_BOOTSTRAP instead of listing ~its content individually.

[DY]LD_LIBRARY_PATH needs to be set to all of installdir's ure and program as
well as OUTDIR, as initPoniesMode (pyuno/source/module/pyuno_module.cxx) tries
to load the OUTDIR test library.  Abstracted as gb_PythonTest_PRECOMMAND.

Abstracted Mac's special LibreOffice.app/Content path as gb_DEVINSTALLROOT,
adapted a number of places accordingly.

Change-Id: I1646615c77dfab342675f84dbb83c579bf16058d