1. change some directory structure for the build script

2. add build script and document
   see DOC/BuildVentoyFromSource.txt for detail

vtoyfat/fat_io_lib/README.txt

@@ -1,3 +0,0 @@
-========= About fat_io_lib =========
-1. Download fat_io_lib source code from http://ultra-embedded.com/releases/fat_io_lib.zip
-2. decompress the code and run buildlib.sh

vtoyfat/fat_io_lib/buildlib.sh

@@ -1,8 +1,16 @@
 #!/bin/sh
 
+if ! [ -f fat_io_lib.zip ]; then
+    echo "No fat_io_lib.zip found ..."
+    exit 1
+fi
+
+unzip fat_io_lib.zip
+
 rm -rf include
 rm -rf lib
 
+
 cd release
 gcc -O2 -D_FILE_OFFSET_BITS=64 fat*.c -c
 ar -rc libfat_io_64.a *.o