(load-parent): New rule, extracted from 'initilize'.
(load-jamfile): If loading project-root.jam, check for
Jamfile and load it in the same module.
(inherit-attributes): Simplify.
(project-rules.constant, project-rules.path-constant): New rules.
* build/targets.jam
(project-target.__init__): New paramater 'parent'.
(project-target.inherit)
(project-target.add-constant)
(project-target.intern-constants): New rules
*
[SVN r26251]
