[reSIProcate] auto_ptr / shared_ptr strategy

[Daniel Pocock]

Here is what I plan to do:

- the master branch will be forked before the auto_ptr / shared_ptr
changes are merged.  1.12.x releases will be made from the fork and they
will not include those changes

- when I make a 1.13.0 tag, it will include the auto_ptr / shared_ptr
changes

- any future bug fixes that urgently need to be used on the 1.12.x
branch can be cherry-picked from latest master using "git cherry-pick"

I hope that this strategy will make it easy for people to choose which
version they will follow and when they will jump from 1.12.x to 1.13.x