Use some version checking on generator scripts, preventing a full rebuild on every build

scripts/gen_usage.sh

@@ -1,10 +1,18 @@
 #! /bin/bash
 # Used to generate usage text from markdown
 
+FILE="$1"
+TEMP="${FILE}_tmp"
+
 cat README.md                        \
     | sed -E 's/^#+ //g'               \
     | sed -E 's/^	/\\t/g'              \
     | sed -E 's/^    /\\t/g'            \
     | sed -E 's/^/\"/'                  \
     | sed -E 's/$/\\n\"/'               \
-    > $1
+    > $TEMP
+
+# If no difference
+if [ ! -e $FILE ] || [ ! -z "$( diff $TEMP $FILE )" ]; then
+	mv -f $TEMP $FILE
+fi