Vector copy now works, or at least, looks like it does.
treee5061a70738c77b8c050143f2dc50fc71bf9d6c3
-rw-r--r-- 10951 library.scm
-rw-r--r-- 69175 picobit-vm.c
-rw-r--r-- 111462 picobit.scm
-rw-r--r-- 388 red-green.scm
-rw-r--r-- 31589 robot.scm