This reverts commit 2a59d2ae.

This reverts commit f4163b8b.

Because apparently, while designing the Objective-C language, somebody
thought it was a world-class idea to allow any white-space between the
'@' character and the subsequent keyword. With this fix, we now
correctly parse:
    @  dynamic
and:
    @
      selector
and:
    @"foo"
     "bar"
    @"mooze"
(This last one is 1 single string split over multiple lines.)
Wonderful, isn't it?

What we (and Clang) do not support, but what GCC supports is something
like:
   @"foo"@@  "bar"  @"mooze"  @@
which is equivalent to @"foobarmooze".

Also removed the (conditional) invoke_token from DeclarationAST and use
the qt_invokable_token to store the Q_INVOKABLE, and fixed the ASTMatch
code generation.

Fixed semantic check for ObjC fast-enumeration for-loops, then merged it with the semantic check for the foreach.