Support for a "forindex(idx; list) {...}" construct analagous to

Support for a "forindex(idx; list) {...}" construct analagous to
foreach, except that the variable gets the index instead of the list
element.  Should be useful, and took almost no code to implement.

Support for operator/assignment syntax: +=, -=, *=, /= and ~= now do
what you think they should.

Library support for a bind() function (see the docs Andy is still
writing), allowing runtime modifications to function lexical
environments.