* conf/common.rmk (pkglib_MODULES): Add bufio.mod.
(bufio_mod_SOURCES): New macro.
(bufio_mod_CFLAGS): Likewise.
(bufio_mod_LDFLAGS): Likewise.
* include/grub/bufio.h: New file.
* io/bufio.c: Likewise.
* video/png.c: Replace <grub/file.h> with <grub/bufio.h>.
(grub_video_reader_png): Use grub_buffile_open to open file.
* video/jpeg.c: Replace <grub/file.h> with <grub/bufio.h>.
(grub_video_reader_jpeg): Use grub_buffile_open to open file.
* video/tga.c: Replace <grub/file.h> with <grub/bufio.h>.
(grub_video_reader_tga): Use grub_buffile_open to open file.
* font/manager.c: Include <grub/bufio.h>.
(add_font): Use grub_buffile_open to open file.
* video/reader/png.c (grub_png_data): New member is_16bit and
image_data.
(grub_png_decode_image_header): Detect 16 bit png image.
(grub_png_convert_image): New function to convert 16 bit image to 8 bit.
(grub_png_decode_png): Call grub_png_convert_image for 16 bit image.
(grub_video_reader_png): Release memory occupied by image_data.
* fs/ntfs.c (find_attr): Handle non-resident attribute list larger than
4096 bytes.
(grub_nfs_mount): Skip the test for sector per cluster.
* include/grub/ntfs.h (MAX_SPC): Removed.
