Updated Featherweight Defenders model

[Brian Goetz]

I've posted an updated version of the Featherweight Defenders model, 
which addresses three issues, the latter two of which should be welcome 
changes to some members of this forum:

  - Revised handling of super-call restrictions to merge with treatment 
of inheritance.  The current restrictions include the restriction to an 
immediate super-type, and also are restricted to linkage targets that 
would be inheritance candidates of the current class (no "level skipping.")

  - Elimination of "default none"; reversion to two-state treatment of 
interface methods (abstract and default);

  - Treat explicit redeclaration of a method in an interface as 
reabstraction.

The actual changes are surprisingly small; there are changes in the 
R-XxxSuper rules, T-IntExpl, R-IntDef, R-IntInh, and R-ClassInh.

See: 
http://cr.openjdk.java.net/~briangoetz/lambda/featherweight-defenders.pdf

The implementation in openjdk (both compiler and VM) is slightly behind 
this document draft, but should be updated soon.