Add alt code, PDF + format/typo checks 2011/zucker

The alt code is based on the author's remarks - it sets binary mode on
stdout.

The PDF is about sphere tracing. Added it in case the link ever dies.

Format/typo check README.md file.

Updated .gitignore.

2011/zucker/Makefile

@@ -114,8 +114,8 @@ OBJ= ${PROG}.o
 DATA=
 TARGET= ${PROG}
 #
-ALT_OBJ=
-ALT_TARGET=
+ALT_OBJ= ${PROG}.alt.o
+ALT_TARGET= ${PROG}.alt
 
 
 #################
@@ -138,6 +138,9 @@ ${PROG}: ${PROG}.c
 alt: data ${ALT_TARGET}
 	@${TRUE}
 
+${PROG}.alt: ${PROG}.alt.c
+	${CC} ${CFLAGS} $< -o $@ ${LDFLAGS}
+
 # data files
 #
 data: ${DATA}