message: skip_palette->indexed_color; remove constructor but use a setter
diff: @@ -544,7 +544,7 @@ pub struct BmpDecoder<R> {
  reader: R,
  bmp_header_type: BMPHeaderType,
  - skip_palette: bool,
  + indexed_color: bool,
  width: i32,
  height: i32,
  @@ -629,17 +629,11 @@ impl<'a, R: Read> Iterator for RLEInsnIterator<'a, R> {
  impl<R: Read + Seek> BmpDecoder<R> {
  /// Create a new decoder that decodes from the stream ```r```
  pub fn new(reader: R) -> ImageResult<BmpDecoder<R>> {
  - Self::new_skip_palette(reader, false)
  - }
  -
  - /// Create a new decoder that decodes from the stream ```r```
  - /// If ```skip_palette``` is true, the palette in BMP is skipped even if found.
  - pub fn new_skip_palette(reader: R, skip_palette: bool) -> ImageResult<BmpDecoder<R>> {
  let mut decoder = BmpDecoder {
  reader,
  bmp_header_type: BMPHeaderType::Info,
  - skip_palette,
  + indexed_color: false,
  width: 0,
  height: 0,
  @@ -666,7 +660,7 @@ impl<R: Read + Seek> BmpDecoder<R> {
  reader,
  bmp_header_type: BMPHeaderType::Info,
  - skip_palette: false,
  + indexed_color: false,
  width: 0,
  height: 0,
  @@ -687,6 +681,12 @@ impl<R: Read + Seek> BmpDecoder<R> {
  Ok(decoder)
  }
  + /// If true, the palette in BMP does not apply to the image even if it is found.
  + /// In other words, the output image is the indexed color.
  + pub fn set_indexed_color(&mut self, indexed_color: bool) {
  + self.indexed_color = indexed_color;
  + }
  +
  #[cfg(feature = "ico")]
  pub(crate) fn reader(&mut self) -> &mut R {
  &mut self.reader
  @@ -1029,7 +1029,7 @@ impl<R: Read + Seek> BmpDecoder<R> {
  }
  fn num_channels(&self) -> usize {
  - if self.skip_palette {
  + if self.indexed_color {
  1
  } else if self.add_alpha_channel {
  4
  @@ -1074,7 +1074,7 @@ impl<R: Read + Seek> BmpDecoder<R> {
  let bit_count = self.bit_count;
  let reader = &mut self.reader;
  let width = self.width as usize;
  - let skip_palette = self.skip_palette;
  + let skip_palette = self.indexed_color;
  reader.seek(SeekFrom::Start(self.data_offset))?;
  @@ -1462,7 +1462,7 @@ impl<'a, R: 'a + Read + Seek> ImageDecoder<'a> for BmpDecoder<R> {
  }
  fn color_type(&self) -> ColorType {
  - if self.skip_palette {
  + if self.indexed_color {
  ColorType::L8
  } else if self.add_alpha_channel {
  ColorType::Rgba8
  