Use the free variables in the named properties from the term instead of the
ones on the list.  Another small step towards the optimization to the list.
Skip free vars while doing deep-equal.
Get free variables from the term in this case too.
Another place of using the free variables from the term instead of from the
property list.
Also add two TODO comments for old issues with reference counting in the
code that should be revisited.
Use the buffer's free vars instead of the free vars on the buffer's
property list.