Add support for //foo/bar:allrec to build all targets in foo/bar/BUILD
and below.

Fix for transitive dependence in translate_and_compile.  E.g., when
proto_libriary p1 depends on proto_library p2, a binary foo that
depends on p1 also depends on p2.  Hence, cc_library subnode for p1
must inherit dependences from its parent node.

Fixes for absolute paths in gendir, etc.

Changes by Mike for python.