Allow to specify target ids in command line.

    * project.jam (lookup-with-load): New rule.
      (find-target): Try interperting target id as project first.

    * build-request.jam (from-command-line): Don't grab
      unconditionally elements which have slashes -- they may be target
      ids.

    * build-system.jam: Allow target ids is command
      line. Accept --clean option.

    * BoostBuild.py (run_build_system): Call 'ignore_directoies' on diff.

    * tree.py (Trees_different.ignore_directoies): New method.


[SVN r15768]

tools/build

@@ -1 +1 @@
-Subproject commit 742e30850e6bf4bdcad27500a5c75475a32e9c89
+Subproject commit 4b5d5cc6e4a500c522e8e03a4e95d546301034d1