Support Libraw 0.19

[SamWhited]

There's something wrong with these and I get an out of memory exception if I try to do anything. It's late; backing them up here now for early review and will look at them again later.

[SamWhited]

>>> myphoto = edit(filename='RAW_CANON_EOS_7D.CR2')
Exception in thread Thread-4:
Traceback (most recent call last):
  File "/usr/lib64/python3.7/threading.py", line 917, in _bootstrap_inner
    self.run()
  File "/usr/lib64/python3.7/threading.py", line 865, in run
    self._target(*self._args, **self._kwargs)
  File "/home/sam/Projects/photorepl/photorepl/photo.py", line 89, in _update
    self.save(filename=self.tempfile, filetype='ppm')
  File "/home/sam/Projects/rawkit/rawkit/raw.py", line 158, in save
    self.process()
  File "/home/sam/Projects/rawkit/rawkit/raw.py", line 125, in process
    self.libraw.libraw_dcraw_process(self.data)
  File "/home/sam/Projects/rawkit/libraw/errors.py", line 129, in check_call
    raise_if_error(exit_code.value)
  File "/home/sam/Projects/rawkit/libraw/errors.py", line 171, in raise_if_error
    }[error_code]
libraw.errors.InsufficientMemory

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/sam/Projects/photorepl/photorepl/__main__.py", line 24, in edit
    photo = Photo(filename=filename, ui_thread=ui_thread)
  File "/home/sam/Projects/photorepl/photorepl/photo.py", line 54, in __init__
    self.show()
  File "/home/sam/Projects/photorepl/photorepl/photo.py", line 81, in show
    rawfile=self.filename
  File "/home/sam/Projects/photorepl/photorepl/threads.py", line 41, in open_window
    return Preview(filename=filename, rawfile=rawfile, show=True)
  File "/home/sam/Projects/photorepl/photorepl/views/preview.py", line 38, in __init__
    self.render_photo(filename)
  File "/home/sam/Projects/photorepl/photorepl/views/preview.py", line 73, in render_photo
    pix = GdkPixbuf.Pixbuf.new_from_file_at_size(filename, 800, 600)
  File "<string>", line 38, in new_from_file_at_size
GLib.GError: Couldn’t recognize the image file format for file “/tmp/tmpjiqmro5t”

[SamWhited]

This might be LibRaw/LibRaw#171, will build a newer version and double check.

EDIT: yup, everything seems fine on LibRaw/LibRaw@06028d0