Virtual extension methods -- a strawman design

[Brian Goetz]

The attached document reflects our current thinking in the area of extension 
methods, which was introduced in section 8 of the Strawman proposal.  This 
document (arguably) improves on the static extension method scheme presented 
there.

Comments on the technical merits and flaws of the scheme are welcome (there 
are lots of details to be fleshed out, of course.)  Comparisons to the 
previous (static) extension method scheme outlined in the strawman are also 
fair game.

Comments to the effect of "I like XYZ other scheme better" are not.  (Where 
XYZ could be use-site extension methods, traits, mixins, etc.  Those have 
already been considered and rejected as viable approaches for Project Lambda.)