Add self-contained nightly build script "nightly-self-contained".

"nightly-self-contained" follows the official "nightly" script's
directory layout, i.e., $HOME/autobuild/, and will create missing
directories/files from upstream Sable GitHub sources.

Moreover, since non-Sable dependencies have been largely included in
upstream Sable GitHub repos, "nightly-self-contained" will only pull and
build Sable dependencies (i.e., Jasmin, Heros, and Soot), all from the
GitHub repo.

A side benifit is that only "git", "wget", "ant", and "java" are needed.
No more "cvs" and "svn".

Usage: "./nightly-self-contained" # that is it!

After build finish, find Soot's nightly jars and javadoc under
"$HOME/autobuild/releases".