New: @ref and @deref in Objective-J 2.0.
Unit test @ref and @deref.
New: use @ref and @deref instead of Ref.h throughout Cappuccino.
New: optimise CPArray enumerateObjectsWithOptions:usingBlock:.
Fixed: CPNumberFormatter formatted @"" as any number.

Without this fix, `- CPNumberFormatter getObjectValue:forString:errorDescription:` would return `YES` for string @"", like if it was properly converted to an object value, but then actually leave object value unchanged.

With this fix object value is set to nil like in Cocoa.

Refs #1829.
Test: expand CPNumberFormatter test to be more complete.

- Cover the formatting of @"" to nil.
- Check error messages by reference.
- Check output values.
- use @ref() instead of hand coded AT_REF.

Refs #1829.
New: update operators on references, such as `@deref(x)++`.

This fix implements support for both prefix and postfix update operators on a dereference.
New: @deref(<any idempotent expression>).

This change makes it possible to @deref any expression, such as a conditional expression, as long as the expression doesn't have side effects.

The reason not to allow dereferencing of expressions with side effects is that we might need to evaluate the expression twice in certain uses of deref, which is not obvious when you look at the deref operator in plain code.
Formatting: simplify code slightly.
Merge branch 'master' of github.com:cappuccino/cappuccino