rename snapfs-core-2.4.20.patch to ext3-snapfs-2.4.20.patch, resolve some confilcts after add ext3-extents patch, some minor fix

1)In migration, get rid of page and buffer of src inode(fs_flushinval_pages). 2)fix some lock problems in ext3_create_indirect

1 add some initial snapfs process in ext3_readsupre, 2 get rid of copy_block for reguarl file in snapfs kernel patch

update snapfs kernel patch 1)rewrite ext3_copy_blk according to the generic_file_write 2)get rid of some useless code 3)some minor fix in debug print