Additional Image Loaders

[ErichZimmer]

Currently, only two image loaders are supported: tif/tiff and pgm loaders. I plan on expanding this to more image types as I learn how the image loaders operate and when I take a college course on c++ and OOP so I can contribute better to this repository.

Note: these are the image types I used at least once with commercial PIV software and OpenPIV-Python.

Image loaders:

• bmp loader (use easyBMP since it actually looks quite easy to use)
• jpg/jpeg loader (we already have libjpeg)
• png loader (use spng since it is in meson wrap database, but libpng would do too)
• raw loader (use libRAW)
• tif/tiff loader
• webp loader (use libwebp since it is in meson wrap database)

This would have a nice side effect of diversifying the image loaders for the python bindings so I don't have to rely on the buffer protocol to copy a loaded image from the imageio python package to an image_gf instance.