add make genpath rules, .path files, updated .top and .year

Add .path files to each winner directory: a file containing
the path to the winner directory from the top directory.

Changed YYYY/.year files to contain the paths, from the top
directory, if the winning directories for the given year.

Changed `/.top` to contain the IOCCC years.

Added `make genpath` rule to the top Makefile and the
year Makefiles to generate the above.

Added FAQ 6.8 to `faq.md` to explain the above.

Updated manifest to reflect recent changes to the list of files.

1988/.year

@@ -1 +1,9 @@
-1988
+1988/applin
+1988/dale
+1988/isaak
+1988/litmaath
+1988/phillipps
+1988/reddy
+1988/robison
+1988/spinellis
+1988/westley