img2img works with all samplers, inpainting working with ddim & plms

- img2img confirmed working with all samplers
- inpainting working on ddim & plms. Changes to k-diffusion
  module seem to be needed for inpainting support.
- switched k-diffuser noise schedule to original karras schedule,
  which reduces the step number needed for good results

scripts/dream.py

@@ -324,6 +324,7 @@ def main_loop(gen, opt, infile):
                 opt.last_operation='generate'
                 gen.prompt2image(
                     image_callback=image_writer,
+#                    step_callback=gen.write_intermediate_images(5,'./outputs/img-samples/intermediates'), #DEBUGGING ONLY - DELETE
                     catch_interrupts=catch_ctrl_c,
                     **vars(opt)
                 )