Fixed: problem when depending on two targets redo-always using redo-stamp

Added test case.

Updated redo-ifchange to continue probing for dirty sub-targets until no
sub-targets are found anymore and either the current target is dirty, or
is clean.
fixup-t660-stamp
Fix test 130: ls -l output is not always as expected
Change the process title with a cleaned-up version of the script
Document the use of setproctitle in the README
Implemented --overwrite
Add locking of deps files
Redo state now stored in .redo subdirectory
Fixup test with --overwrite