- Allow this for both argument lists and block arguments.
- Tweak precedence to make "." higher than infix "{}" to avoid a
class body being parsed as the superclass clause's block argument.
- Convert all uses of ".call" to use this. (There was not a single
case in the repo that ran into the getter ambiguity.)
This fixes the nasty case where "foo(bar)" is context-sensitive, and
generally simplifies the compiler a lot since there is a clear
distinction between lexical and dynamic scope.
Also:
- Remove the special handling of capitalized names since all names are
lexical now.
- Allow methods to close over local variables in enclosing functions.
- Allow implicit definition of all lexical names.
