STLplus C++ library collection SVN stlplus3

Added general information to make a README suitable for the SF website

Documented v3.8 changes

patch fixing bug where removing the first/last node/arc left pointers dangling

Corrected -ldl linker directive which is a load library, not a flag

Added recent tests

Documented changes: double-destruct-proof simple_ptr and smart_ptr;
fix bug in ntree

Added a test for the cut method to confirm the bug fix.

DJDM reported that he had had a special case where a dependency loop
caused the double-destruction of a simple_ptr. This is a fix to both
simple_ptr (from DJDM) and to smart_ptr (by AJR) to prevent such a
situation from causing a crash.

Fixed bug in ntree::cut where an old method name set_new_owner was
being called instead of the newer version change_owner. This is an old
bug, first reported about 1 year ago and the fix got lost.

Changed exit ststus to success if the shared_ptr class is missing
since this is the expected outcome.