IMG-25: load ICO files (#1458)

* disk_sink + fixes

* Always 4 bands for v3+ bmp on save

* bmpsave fixed (w/o orientation)

* fixed ico for target save

* icosave.c

* Removed leftover comments

* icoload.c

* Row buffer (skripatch) is not needed anymore

* Minor fixes for icoload/save

* Use wips_image_write instead of vips_copy

* Forgotten &

* Check resulting dimensions

* -debug printf

vips/bmp.h

@@ -26,6 +26,8 @@ VIPS_API
 int vips_bmpload_source(VipsSource *source, VipsImage **out, ...)
     G_GNUC_NULL_TERMINATED;
 int vips_bmpload_source_go(VipsImgproxySource *source, VipsImage **out);
+int
+vips_bmpload_buffer(void *buf, size_t len, VipsImage **out, ...);
 
 // defined in bmpsave.c
 int vips_bmpsave_target_go(VipsImage *in, VipsTarget *target);