Add 2004/sds/try.sh + format/typo checks

The try.sh script runs what used to be in the try section.

Format/typo fix README.md in full. This commit also fixes an
inconsistency where the author unwittingly used the word stenography
instead of steganography, a very easy mistake to make and one that I
almost missed.

Updated Makefile to silence a couple warnings.

Updated .gitignore.

2004/sds/Makefile

@@ -38,7 +38,8 @@ include ../../var.mk
 
 # Common C compiler warnings to silence
 #
-CSILENCE= -Wno-unsequenced -Wno-unused-value -Wno-strict-prototypes
+CSILENCE= -Wno-unsequenced -Wno-unused-value -Wno-strict-prototypes -Wno-unused-parameter \
+	  -Wno-implicit-int
 
 # Common C compiler warning flags
 #