Adds function image_copy_ref to image module for getting a new reference
to an image. It can be used instead of image_make_subimage when the
sizes of the original and the subimage are same.
- Use the existing bitstream_t type to give access to the bitstream.
We can extend it later to make it a linked list like I was planning
to do with the payload type.
- The main encoder now also stores the bitstream in memory.
- Move image_t and pixel_t to the kvazaar.h API.
- Try and arrange things such that image_t can be used as input and
output for encoding.
Conflicts:
src/encmain.c
