Get all 1986 entries to compile

1986/wall will not compile under the default gcc (as it's actually
clang) with macOS as it requires -traditional-cpp which unfortunately
clang does not support.

Also fixed many of the README.md files.

Removed 1986/bright/bright.orig.c (probably because it won't compile on
modern systems but maybe not; I did that change a while back but didn't
finish working on 1986 until just now).

1986/wall/README.md

@@ -10,9 +10,10 @@ US of A
 
         make all
 
-NOTE: This entry uses non-standard args to main() that do not work with modern compilers.
 
-NOTE: This entry requires a non-standard K&R C compiler to compile.
+NOTE: On modern systems this entry requires the option `-traditional-cpp` which
+clang does not support. Please be advised that gcc under macOS is actually
+clang so this will not compile with the default gcc under macOS.
 
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