OpenImageIO 2.2.7.0

This is the latest monthly instalment of the current supported production release series. It is API and ABI compatible with prior 2.2 releases.

Release 2.2.7 (1 Oct 2020) -- compared to 2.2.6

• oiiotool new command: --pastemeta takes two images as arguments, and
  appends all the metadata (only) from the first image onto the second
  image's pixels and metadata, producing a combined image. #2708
• TIFF: Fix broken reads of multi-subimage non-spectral files (such as
  photometric YCbCr mode). #2692
• Python: When transferring blocks of pixels (e.g., ImageInput.read_image()
  or ImageOutput.write_scanline()), "half" pixels ended up mangled into
  uint16, but now they use the correct numpy.float16 type. #2694
• Python: The value passed to attribute(name, typedesc, value) can now be
  a tuple, list, numpy array, or scalar value. #2695
• IBA::contrast_remap() fixes bug that could crash for very large images
  #2704
• Warn about recommended minimum versions of some dependencies.
• Windows fix: correct OIIO_API declaration on aligned_malloc, aligned_free
  of platform.h. #2701
• Fix oiiotool crash when --resize was used with multi-subimage files. #2711
• Bug fix in Strutil::splits and splitsv: when input is the empty string,
  the split should return no pieces. #2712
• Support for libheif 1.9. #2724
• TIFF: Fix spec() and spec_dimensions() for MIPmapped TIFF files, they
  did not recognize being asked to return the specs for invalid subimage
  indices. #2723
• TIFF: add ability to output 1bpp TIFF files. #2722