Say goodbye to the composing-generator class.

* new/generators.jam
    (generator): New argument 'composing'
    (run): Use 'self.composing'.
    (convert-multiple-sources-to-consumable-types): Moved from
       composing-generator.
    (composing-generator): Remove

* new/builtin.jam
    (linking-generator, register-linker): Use the argument to generator's
       ctor. Allow to make generator non-composing.

* new/msvc.jam: Make msvc.link generator non-composing.


[SVN r17572]

tools/build

@@ -1 +1 @@
-Subproject commit 1ffb2b163f36eed95cf98c09f525b07072afe455
+Subproject commit a0a781467ab22cb5aa290250302d62a4df298288