message: Bugfix DXT3/5 support
diff: //! # Related Links
  //! * <https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_compression_s3tc.txt> - Description of the DXT compression OpenGL extensions.
  //!
  +//! Note: this module only implements bare DXT encoding/decoding, it does not parse formats that can contain DXT files like .dds
  use std::io::{Read, Write};
  @@ -73,7 +74,7 @@ impl <R: Read> DXTDecoder<R> {
  /// to be passed in ```width``` and ```height```, as well as the
  /// DXT variant in ```variant```.
  /// width and height are required to be powers of 2 and at least 4.
  - /// otherwise an error will be returend
  + /// otherwise an error will be returned
  pub fn new(r: R, width: u32, height: u32, variant: DXTVariant) -> Result<DXTDecoder<R>, ImageError> {
  if width % 4 != 0 || height % 4 != 0 {
  return Err(ImageError::DimensionError);
  @@ -109,7 +110,7 @@ impl <R: Read> ImageDecoder for DXTDecoder<R> {
  }
  fn read_scanline(&mut self, buf: &mut [u8]) -> ImageResult<u32> {
  - let mut src = vec![0u8; DXTVariant::DXT1.encoded_bytes_per_block() * self.width_blocks as usize];
  + let mut src = vec![0u8; self.variant.encoded_bytes_per_block() * self.width_blocks as usize];
  self.inner.read_exact(&mut src)?;
  match self.variant {
  DXTVariant::DXT1 => decode_dxt1_row(&src, buf),
  