Add start of Debian packaging scripts.

To use these scripts:
* Download a release of WiredTiger
* Unpack the package, and rename a version of the package to be:
   wiredtiger_X.X.X.orig.tar.bz2 (note underscore)
* Add the content of dist/package/debian to a folder into a 'debian'
  folder of the package you unpacked (I'm not sure if this is required)
* From the root directory, run "debuild -us -uc"
Clarify a comment.
Merge branch 'develop' into new-split
Fix up a comment in the walk code: we can't see restart on an ascent
hazard pointer couple.
Rewrite the big comment about how we're handling removed on-page
overflow key/value items during page save/restore.
Merge branch 'new-split' into new-split-fixes