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/august/Makefile

@@ -184,6 +184,7 @@ all: ${DATA} ${TARGET}
 	supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
+	@echo "NOTE: this entry is very likely to dump core after its output."
 	${CC} ${CFLAGS} $< -o $@ ${LIBS}
 
 # alternative executable